Magnetocaloric effect and refrigerant capacity in SmSrMnO (x = 0.42, 0.44, 0.46) manganites
Nicholas S. Bingham, Paula J. Lampen, The-Long Phan, Manh-Huong Phan, Seong-Cho Yu et al.
SmSrMnO (SSMO) with x ~ 0.44 shows a multi-critical phase diagram which includes antiferromagnetic, charge ordering, and ferromagnetic transitions that give rise to large magnetoresistive and magnetocaloric effects. In this study, we systematically investigated the magnetic transitions, magnetocalor ... [J. Appl. Phys. 111, 07D705 (2012)] published Mon Feb 13, 2012.
Properties of NaZn-type LaFeSi (x=1.4, 1.5) compound with the first-order phase transition
Q. Y. Dong, H. W. Zhang, J. Shen, J. Chen, J. R. Sun et al.
The investigations of dc magnetization, magnetic relaxation, specific heat, and electrical resistance for LaFeSi (x = 1.4, 1.5) compounds have been carried out. Obvious thermal and magnetic hysteresis indicates that they experience a first-order phase transition. The phase transition temperature T i ... [J. Appl. Phys. 111, 07E107 (2012)] published Mon Feb 13, 2012.
Magnetic properties of single crystal EuCoAs
Jared Ballinger, Lowell E. Wenger, Yogesh K. Vohra, and Athena S. Sefat
Magnetization measurements at ambient pressure have been performed on single crystal EuCoAs, a compound having a similar crystalline structure as the pressure-induced EuFeAs superconductor. Similar to the magnetic characteristics of EuFeAs at ambient pressure, the effective paramagnetic moment at hi ... [J. Appl. Phys. 111, 07E106 (2012)] published Mon Feb 13, 2012.
Field-induced continuous rotation of the polarization in multiferroic MnCoWO
K.-C. Liang, R. P. Chaudhury, Y. Q. Wang, Y. Y. Sun, B. Lorenz et al.
We report the observation of a continuous rotation of the polarization in MnCoWO under magnetic field. At zero field, this compound shows a transition into the spiral magnetic and ferroelectric phase at 12.2 K, which is the ground state, with the polarization oriented along the b-axis. Increasing b- ... [J. Appl. Phys. 111, 07D903 (2012)] published Mon Feb 13, 2012.
Thermal issues and their effects on heat-assisted magnetic recording system (invited)
B. X. Xu, Z. J. Liu, R. Ji, Y. T. Toh, J. F. Hu et al.
Compared to the conventional magnetic recording, the big difference in the heat-assisted magnetic recording (HAMR) is the introduction of the thermal energy. It is necessary to study the thermal effects on the HAMR system which includes the head, the media, the head and disk interface (HDI) and data ... [J. Appl. Phys. 111, 07B701 (2012)] published Mon Feb 13, 2012.
Magnetic properties and microstructure of Nd-Fe-B sintered magnets with DyH addition
Y. H. Liu, S. Guo, X. M. Liu, D. Lee, and A. R. Yan
The effects of DyH addition on magnetic properties and microstructure of Nd-Fe-B sintered magnets were investigated. In order to obtain the best magnetic properties, the effects of sintering temperature and annealing time on magnetic properties were also investigated. The results shown that the addi ... [J. Appl. Phys. 111, 07A705 (2012)] published Mon Feb 13, 2012.
Study of surface effects on CoCu nanogranular alloys by ferromagnetic resonance
A. Garcia Prieto, M. L. Fdez-Gubieda, L. Lezama, and I. Orue
Room temperature ferromagnetic resonance measurements have been performed on CoCu melt-spun nanogranular alloys. Results on the ratio of the orbital-to-spin magnetic moment have been compared to previous results obtained by x-ray magnetic circular dichroism, explaining the differences in terms of th ... [J. Appl. Phys. 111, 07C105 (2012)] published Mon Feb 13, 2012.
Hysteresis losses in a dense superparamagnetic nanoparticle assembly
S. A. Gudoshnikov, B. Ya. Liubimov, and N. A. Usov
The hysteresis losses of a dense assembly of magnetite nanoparticles with an average diameter D = 25 nm are measured in the frequency range f = 10 200 kHz for magnetic field amplitudes up to H = 400 Oe. The low frequency hysteresis loops of the assembly are obtained by means of integration of the e ... [AIP Advances 2, 012143 (2012)] published Mon Feb 13, 2012.
Graphene nanodots with intrinsically magnetic protrusions
Michael R. Philpott and Yoshiyuki Kawazoe
The three step auf bau of a triangular polyaromatic protrusion attached to a larger parent hexagonal shaped graphene nanodot (GND) is described and the dichotomy between intrinsic protrusion localized magnetism and parent extended zigzag edge magnetism is explored using ab initio density functional ... [J. Chem. Phys. 136, 064706 (2012)] published Mon Feb 13, 2012.
Anisotropic bimodal distribution of blocking temperature with multiferroic BiFeO epitaxial thin films
C. K. Safeer, M. Chamfrault, J. Allibe, C. Carretero, C. Deranlot et al.
Controlling BiFeO (BFO)/ferromagnet (FM) interfacial coupling appears crucial for electrical control of spintronic devices using this multiferroic. Here, we analyse the magnetic behaviour of exchange-biased epitaxial-BiFeO/FM bilayers with in-plane or out-of-plane magnetic anisotropies. We report bi ... [Appl. Phys. Lett. 100, 072402 (2012)] published Mon Feb 13, 2012.
Coherent Manipulation of Electron Spins in the {Cu} Spin Triangle Complex Impregnated in Nanoporous Silicon
K.-Y. Choi, Z. Wang, H. Nojiri, J. van Tol, P. Kumar et al.
We report on coherent manipulation of electron spins in an antiferromagnetically coupled spin triangle {Cu-X} (X=As, Sb) impregnated in freestanding nanoporous silicon (NS) by using 240 GHz microwave pulses. Rabi oscillations are observed and the spin coherence time is found to be T=1066 ns at 1.5 ... [Phys. Rev. Lett. 108, 067206 ] published .
Indications of an Electronic Phase Transition in Two-Dimensional Superconducting YBaCuO Thin Films Induced by Electrostatic Doping
Xiang Leng, Javier Garcia-Barriocanal, Boyi Yang, Yeonbae Lee, J. Kinney et al.
We successfully tuned an underdoped ultrathin YBaCuO film into the overdoped regime by means of electrostatic doping using an ionic liquid as a dielectric material. This process proved to be reversible. Transport measurements showed a series of anomalous features compared to chemically doped bulk sa ... [Phys. Rev. Lett. 108, 067004 ] published .
Determination of spin pumping as a source of linewidth in sputtered CoFe/Pd multilayers by use of broadband ferromagnetic resonance spectroscopy
Justin M. Shaw, Hans T. Nembach, and T. J. Silva
We performed a systematic study of damping in CoFe/Pd multilayers by use of broadband (160 GHz) ferromagnetic resonance (FMR) spectroscopy in the perpendicular geometry. The data were fitted with the conventional Landau-Lifshitz equation in conjunction with an inhomogeneous contribution to linewidth ... [Phys. Rev. B 85, 054412 ] published .
Thickness-dependent converse magnetoelectric coupling in bi-layered Ni/PZT thin films
Zheng Li, Jiamian Hu, Li Shu, Ya Gao, Yang Shen et al.
The converse magnetoelectric (ME) effect was investigated in bi-layered Ni/Pb(ZrTi)O (PZT) thin films grown on Si substrates, with different thicknesses of Ni thin layers. By using an AC-mode magneto-optical Kerr effect method, it was revealed that the electric-voltage induced magnetization variatio ... [J. Appl. Phys. 111, 033918 (2012)] published Fri Feb 10, 2012.
Fluctuation-induced conductivity analyses of Be-doped (BiCuLiTl)BaCaCuO superconductors in the critical regime and beyond
Nawazish A. Khan, Qurat-ul-Ain, Umber Firdous, and Shaheryar
We have successfully synthesized (BiCuLiTl)BaCaCuO and (BiCuLiTl)Ba(CaBe)CuO samples and studied their excess conductivity analyses (fluctuation-induced conductivity) of resistivity data. The main objective of such analyses is to investigate the influence of Be-substitution on the superconductivity ... [J. Appl. Phys. 111, 033917 (2012)] published Fri Feb 10, 2012.
Domain rotation induced strain effect on the magnetic and magneto-electric response in CoFeO/Pb(Mg,Nb)O-PbTiO heterostructures
Zhiguang Wang, Ravindranath Viswan, Bolin Hu, Jie-Fang Li, V. G. Harris et al.
The present work shows good control of both magnetic and electric properties with electric and magnetic fields, respectively, for epitaxial CoFeO (CFO) films on Pb(Mg,Nb)O-PbTiO (PMN-PT). X-ray reciprocal space mapping revealed a transformation between a- and c-domains in the PMN-PT under electric f ... [J. Appl. Phys. 111, 034108 (2012)] published Fri Feb 10, 2012.
Enhanced magnetic and electrical properties in amorphous Ge:Mn thin films by non-magnetic codoping
Wenjing Yin, Copeland D. Kell, Li He, Melissa C. Dolph, Chris Duska et al.
Amorphous GeMn thin films have been prepared by co-depositing Ge and Mn on SiO/Si using an ultrahigh vacuum molecular beam epitaxy system. Across a range of growth temperatures and Mn concentrations (2.8 at. %, 10.9 at. %, and 21.3 at. %), we achieved enhanced magnetic and electrical properties with ... [J. Appl. Phys. 111, 033916 (2012)] published Fri Feb 10, 2012.
Enhancing and broadening absorption properties of frequency selective surfaces absorbers using FeCoB-based thin film
Wenyi Ren, Yan Nie, Xuan Xiong, Cui Zhang, Yan Zhou et al.
In this paper, the influence of FeCoB-based magnetic film on the absorption properties of traditional frequency selective surface (FSS) was investigated experimentally. A single-layer Minkowski fractal planar frequency selective surface was chosen, and the laser etching technique was proposed to fab ... [J. Appl. Phys. 111, 07E703 (2012)] published Fri Feb 10, 2012.
Effects of substrate on structure and the magnetic properties of (001)-textured FePt films grown at low temperature
A. M. Zhang, Z. X. Chen, W. Q. Zou, B. Lv, J. J. Ge et al.
(001)-oriented FePt films are deposited, by magnetron sputtering at 300 degrees C, on LaAlO (001), SrTiO (001), and MgO (001) single crystal substrates. The tetragonal distortion, magnetic anisotropy, and the coercive force of the films vary with the substrate. The ordering process is very differen ... [J. Appl. Phys. 111, 07A704 (2012)] published Fri Feb 10, 2012.
Large magnetocaloric effect for magnetic refrigeration from 210 to ~275 K in LaCaMnCoO
Y. D. Zhang, The-Long Phan, and S. C. Yu
We have studied the magnetic properties and magnetocaloric effect in LaCaMnCoO (x = 00.05) prepared by conventional solid-state reaction. Magnetic measurements versus temperature revealed that both magnetization and the Curie temperature (T) decreased gradually with increasing Co content (x); T valu ... [J. Appl. Phys. 111, 07D703 (2012)] published Fri Feb 10, 2012.
E-field tuning microwave frequency performance of CoFeSi/lead zinc niobatelead titanate magnetoelectric coupling composites
Shandong Li, Ming Liu, J. Lou, Shawn Beguhn, Jianpeng Wu et al.
Nanocrystalline CoFeSi Heusler alloy films were deposited on single crystal lead zinc niobatelead titanate substrates. It is revealed that this multiferroic composite exhibits very strong continuously electric field (E-field) tunable microwave frequency characteristics. With an increase of the E-fie ... [J. Appl. Phys. 111, 07C705 (2012)] published Fri Feb 10, 2012.
Effect of deviation from stoichiometric composition on structural and magnetic properties of cobalt ferrite, CoFeO (x = 0.2 to 1.0)
I. C. Nlebedim, J. E. Snyder, A. J. Moses, and D. C. Jiles
The effects of deviation from stoichiometric composition on the structural and magnetic properties of cobalt ferrite, CoFeO (x = 0.2 to 1.0), are presented. Both CoFeO and FeO have a spinel crystal structure, and it might be expected that intermediate compositions would have the same structure. Howe ... [J. Appl. Phys. 111, 07D704 (2012)] published Fri Feb 10, 2012.
Controlling the core-to-core distance of vortex pairs in exchange-biased iron elliptical nanoelements
Felipe F. Oliveira, Thiago R. S. Moura, A. S. Carrico, Ana L. Dantas, and G. O. G. Reboucas
We report a theoretical study of vortex pairs in exchange-biased elliptical iron nanoelements. We show that the remanent state may be tailored to fit vortex pairs with opposite chiralities separated by a diamond-like domain. Flat nanoelements with lateral dimensions ranging from 115 nm x 425 nm to ... [J. Appl. Phys. 111, 07D102 (2012)] published Fri Feb 10, 2012.
Magnetocaloric materials with first-order phase transition: thermal and magnetic hysteresis in LaFeSi and NiMnGa (invited)
K. P. Skokov, V. V. Khovaylo, K.-H. Muller, J. D. Moore, J. Liu et al.
This is a report on a comparative study of thermal and magnetic hysteresis in LaFeSi and NiMnGa polycrystalline samples near their first-order phase transitions by measurements of magnetization and direct measurements of the adiabatic temperature change, DeltaT(H). Based on the obtained M(T) and M(H ... [J. Appl. Phys. 111, 07A910 (2012)] published Fri Feb 10, 2012.
Volume exchange in soft FeCo films of high magnetization
Christoph Mathieu, Hau-Jian Liu, Kristen S. Buchanan, and Venkateswara R. Inturi
Soft FeCo films of high magnetization are a well known integral part of today's magnetic recording heads. Values for the volume exchange, an important parameter since it determines exchange length, domain wall width, and energy are, however, available for few compositions of FeCo in spite of the wid ... [J. Appl. Phys. 111, 07A306 (2012)] published Fri Feb 10, 2012.
Bulk nanocomposite using self-forming core/shell nanoparticles and its magnetic properties for high-frequency applications
Tomohiro Suetsuna, Koichi Harada, Toshihide Takahashi, and Seiichi Suenaga
A bulk nanocomposite composed of tightly packed self-forming core/shell nanoparticles of metal/oxide was fabricated. The crystalline grain size of the nanoparticles, the packing ratio, and the composition were controlled in the nanocomposite, and their effects on the magnetic properties were investi ... [J. Appl. Phys. 111, 07A307 (2012)] published Fri Feb 10, 2012.
Charge density waves condensate as measure of charge order and disorder in EuSrMnO (x = 0.50, 0.58) manganites
Parul Pandey, Nilesh Awari, Rakesh Rana, Abhishek Singh, S. S. Prabhu et al.
We have explored the low-energy excitations in epitaxial thin films of EuSrMnO [x = 0.50: spin-glass with short range charge-order and x = 0.58: long range charge-order] using terahertz time-domain spectroscopy. A finite frequency peak structure in optical conductivity is observed at ~3.5 meV for bo ... [Appl. Phys. Lett. 100, 062408 (2012)] published Fri Feb 10, 2012.
Tantalum nitride superconducting single-photon detectors with low cut-off energy
A. Engel, A. Aeschbacher, K. Inderbitzin, A. Schilling, K. Il'in et al.
Materials with a small superconducting energy gap are expected to favor a high detection efficiency of low-energy photons in superconducting nanowire single-photon detectors. We developed a TaN detector with smaller gap and lower density of states at the Fermi energy than in comparable NbN devices, ... [Appl. Phys. Lett. 100, 062601 (2012)] published Fri Feb 10, 2012.
First-principles characterization of ferromagnetism in N-doped SrTiO and BaTiO
Kesong Yang, Ying Dai, and Baibiao Huang
The spin-polarization and magnetic coupling character of N-doped SrTiO (STO) and BaTiO (BTO) are studied through first-principles calculations. The substitutional N doping at O sites leads to a half-metallic property and produces a magnetic moment of 1.0 [mu]. The magnetic interaction between the ne ... [Appl. Phys. Lett. 100, 062409 (2012)] published Fri Feb 10, 2012.
Formation and structure of 360 and 540 degree domain walls in thin magnetic stripes
Youngman Jang, S. R. Bowden, Mark Mascaro, J. Unguris, and C. A. Ross
360 degrees , 540 degrees , and other complex transverse domain walls have been created in narrow cobalt wires connected to injection pads by cycling a magnetic field perpendicular to the wire length. The composite walls, formed by impingement of 180 degrees transverse walls of alternating chiralit ... [Appl. Phys. Lett. 100, 062407 (2012)] published Fri Feb 10, 2012.
Electronic and magnetic properties of LaNiMnO and LaCoMnO with cationic ordering
Min Zhu, Yong Lin, Edward W. C. Lo, Qiong Wang, Zhengjie Zhao et al.
Employing first-principles electronic structure calculations, the electronic and magnetic properties of LaNiMnO and LaCoMnO with Ni/Mn and Co/Mn ordering in (001), (110), and (111) directions are investigated. The ground states of LaNiMnO and LaCoMnO are ferromagnetic semiconducting with alternative ... [Appl. Phys. Lett. 100, 062406 (2012)] published Fri Feb 10, 2012.
Direct Observation of Unconventional Topological Spin Structure in Coupled Magnetic Discs
C. Phatak, A. K. Petford-Long, and O. Heinonen
Confined magnetic thin films are known to exhibit a variety of fascinating topological spin states such as Skyrmions, vortices, and antivortices. Such topological excitations are fundamentally important to our understanding of quantum critical phenomenon and related phase transitions. Here we report ... [Phys. Rev. Lett. 108, 067205 ] published .
Quantum Ice: A Quantum Monte Carlo Study
Nic Shannon, Olga Sikora, Frank Pollmann, Karlo Penc, and Peter Fulde
Ice states, in which frustrated interactions lead to a macroscopic ground-state degeneracy, occur in water ice, in problems of frustrated charge order on the pyrochlore lattice, and in the family of rare-earth magnets collectively known as spin ice. Of particular interest at the moment are quantum s ... [Phys. Rev. Lett. 108, 067204 ] published .
Magnetotransport at Domain Walls in BiFeO
Q. He, C.-H. Yeh, J.-C. Yang, G. Singh-Bhalla, C.-W. Liang et al.
Domain walls in multiferroics can exhibit intriguing behaviors that are significantly different from the bulk of the material. We investigate strong magnetoresistance in domain walls of the model multiferroic BiFeO by probing ordered arrays of 109 degrees domain walls with temperature- and magnetic ... [Phys. Rev. Lett. 108, 067203 ] published .
Magnetic properties of the doped spin-(1/2) honeycomb-lattice compound InCuVO
Y. J. Yan, Z. Y. Li, T. Zhang, X. G. Luo, G. J. Ye et al.
We report magnetic properties in the Co- and Zn-doped spin-1/2 honeycomb-lattice compound InCuVO. Magnetic susceptibility and specific heat experiments show no long-range ordering down to 2 K in InCuVO. Analyses of electronic structures and states suggest that the ground state of undoped InCuVO is p ... [Phys. Rev. B 85, 085102 ] published .
Reconstructing the bulk Fermi surface and superconducting gap properties from neutron scattering experiments
Tanmoy Das, R. S. Markiewicz, and A. Bansil
We develop an analytical tool to extract bulk electronic properties of unconventional superconductors from inelastic neutron scattering spectra. We show that the upward and downward branches of the spin excitation spectra have distinct origins, with the upper branch representing a gapped spin-wave d ... [Phys. Rev. B 85, 064510 ] published .
Magnetic-field tuned anisotropy in superconducting RbFeSe
S. Bosma, R. Puzniak, A. Krzton-Maziopa, M. Bendele, E. Pomjakushina et al.
The anisotropic superconducting properties of a RbFeSe single crystal with T~=32 K were investigated by means of superconducting quantum interference device (SQUID) and torque magnetometry, probing the effective magnetic penetration depth lambda and the magnetic penetration depth anisotropy gamma. I ... [Phys. Rev. B 85, 064509 ] published .
Phase transitions in spin-orbital models with spin-space anisotropies for iron pnictides: Monte Carlo simulations
Ryan Applegate, Rajiv R. P. Singh, Cheng-Chien Chen, and Thomas P. Devereaux
The common phase diagrams of superconducting iron pnictides show interesting material specificities in the structural and magnetic phase transitions. In some cases the two transitions are separate and second order, while in others they appear to happen concomitantly as a single first-order transitio ... [Phys. Rev. B 85, 054411 ] published .
Enhancement of ferromagnetism in Ni excess CuNiMnSb half Heusler alloys
B. L. Ahuja, Alpa Dashora, Shailja Tiwari, H. S. Mund, Madhumita Halder et al.
Spin momentum densities of CuNiMnSb (for x = 0.17 and 0.22), derived from experimental magnetic Compton profiles (MCPs), show an increase in magnetic moment while going from x = 0.17 --> 0.22, which is attributed to Mn 3d states. MCPs along with magnetization data suggest a negligible contribution o ... [J. Appl. Phys. 111, 033914 (2012)] published Thu Feb 9, 2012.
Angular and frequency dependence of standing spin waves in FePt films
D. M. Jacobi, E. Sallica Leva, N. Alvarez, M. Vasquez Mansilla, J. Gomez et al.
We present a detailed analysis of the dynamic response of the magnetization in as-made FePt thin films, particularly studying the angular dependence of standing spin waves that can be observed when the external field is applied close to the film normal. We have found that the field separation betwee ... [J. Appl. Phys. 111, 033911 (2012)] published Thu Feb 9, 2012.
Imaging of magnetic flux distribution in vicinity of insulating particles in high-T superconductor by electron holography
Zentaro Akase, Hiroto Kasai, Shuichi Mamishin, Daisuke Shindo, Mitsuru Morita et al.
REBaCuO (RE: rare earth) bulk superconductors, whose microstructures can be controlled by quench and melt growth (QMG) processing, have a high critical current density J, which makes them well suited for use in practical applications. Through a combination of electron holography and a focused ion-be ... [J. Appl. Phys. 111, 033912 (2012)] published Thu Feb 9, 2012.
A magnetoelectric multiglass state in multiferroic YbFeO
Y. Sun, Y. Liu, F. Ye, S. Chi, Y. Ren et al.
A multiglass state in which two distinct glassy phases coexist has been identified in multiferroic YbFeO. A collective magnetic freezing, as evidenced by AC susceptibility, magnetization, and coercivity measurements, develops at a freezing temperature T ~ 80 K. Meanwhile, the low-temperature dielect ... [J. Appl. Phys. 111, 07D902 (2012)] published Thu Feb 9, 2012.
Magnetic transitions in erbium at high pressures
Sarah A. Thomas, Georgiy M. Tsoi, Lowell E. Wenger, Yogesh K. Vohra, and Samuel T. Weir
Electrical resistance measurements have been carried out on polycrystalline erbium (Er) at temperatures down to 10 K and pressures up to 20 GPa. An abrupt change in the slope of the resistance is observed with decreasing temperature below 84 K which is associated with the c-axis modulated antiferrom ... [J. Appl. Phys. 111, 07E104 (2012)] published Thu Feb 9, 2012.
Reduction of hysteresis loss and large magnetocaloric effect in the C- and H-doped La(Fe, Si) compounds around room temperature
H. Zhang, B. G. Shen, Z. Y. Xu, X. Q. Zheng, J. Shen et al.
The effects of the interstitial C and H atoms on the phase formation, the hysteresis loss, and magnetocaloric effects of the NaZn-type La(Fe, Si) compounds are investigated. It is found that the annealing time to obtain a 1:13 structure is significantly reduced from 40 days for LaFeSi to a week for ... [J. Appl. Phys. 111, 07A909 (2012)] published Thu Feb 9, 2012.
Room temperature ferromagnetism in monoclinic Mn-doped ZrO thin films
Nguyen Hoa Hong, C.-K. Park, A. T. Raghavender, O. Ciftja, N. S. Bingham et al.
Theory has predicted that high temperature ferromagnetism (FM) should be found in cubic Mn-doped ZrO. Our experimental data reveal room temperature FM in Mn-doped ZrO thin films grown on LaAlO substrates. The largest saturated magnetic moment (M) is found to be about 13.8 [mu]/Mn for the cubic MnZrO ... [J. Appl. Phys. 111, 07C302 (2012)] published Thu Feb 9, 2012.
Surface morphologies and magnetic properties of Fe and Co magnetic thin films on polyethylene naphthalate organic substrates
Hideo Kaiju, Taro Abe, Kenji Kondo, and Akira Ishibashi
We have studied the surface morphologies and magnetic properties of Fe and Co thin films evaporated on polyethylene naphthalate (PEN) organic substrates toward the fabrication of spin quantum cross devices. As a result, the surface roughnesses of Co (6.1 nm)/PEN and Co (12 nm)/PEN are as small as 0. ... [J. Appl. Phys. 111, 07C104 (2012)] published Thu Feb 9, 2012.
Co/Pt multilayer-based magnetic tunnel junctions with perpendicular magnetic anisotropy
Zoe Kugler, Jan-Philipp Grote, Volker Drewello, Oliver Schebaum, Gunter Reiss et al.
Temperature-dependent transport measurements of magnetic tunnel junctions with perpendicularly magnetized Co/Pt electrodes are presented. Magnetization measurements of the Co/Pt multilayers are performed to characterize the electrodes. The interface magnetization of the Co layers at the Pt interface ... [J. Appl. Phys. 111, 07C703 (2012)] published Thu Feb 9, 2012.
Tuning of magnetization dynamics in sputtered CoFeB thin film by gas pressure
Feng Xu, Qijun Huang, Zhiqin Liao, Shandong Li, and C. K. Ong
The influences of sputtering gas pressure on the high-frequency magnetization dynamics of as-sputtered CoFeB thin films are studied with permeability spectra based on the Landau-Lifshitz-Gilbert (LLG) equation. Results show that with the pressure increasing, both the anisotropy field and resonance f ... [J. Appl. Phys. 111, 07A304 (2012)] published Thu Feb 9, 2012.
Magnetocaloric effect in LaPrFeSi compounds with a combined addition of Co and C
Jun Shen and Jin-Liang Zhao
The influence of a combined addition of Co and C on the magnetocaloric effect in the LaPrFeSi compound is investigated. The addition of Co and C can adjust Curie temperature (T) to around room temperature. Although the magnetic entropy change (DeltaS) of LaPrFeCoSiC decreases with the increase of x, ... [J. Appl. Phys. 111, 07A908 (2012)] published Thu Feb 9, 2012.
Variational Numerical Renormalization Group: Bridging the Gap between NRG and Density Matrix Renormalization Group
Iztok Pizorn and Frank Verstraete
The numerical renormalization group (NRG) is rephrased as a variational method with the cost function given by the sum of all the energies of the effective low-energy Hamiltonian. This allows us to systematically improve the spectrum obtained by NRG through sweeping. The ensuing algorithm has a lot ... [Phys. Rev. Lett. 108, 067202 ] published .
Quantum Order-by-Disorder Near Criticality and the Secret of Partial Order in MnSi
Frank Kruger, Una Karahasanovic, and Andrew G. Green
The vicinity of quantum phase transitions has proven fertile ground in the search for new quantum phases. We propose a physically motivated and unifying description of phase reconstruction near metallic quantum-critical points using the idea of quantum order by disorder. Certain deformations of the ... [Phys. Rev. Lett. 108, 067003 ] published .
Manifestly Non-Gaussian Fluctuations in Superconductor-Normal Metal Tunnel Nanostructures
M. A. Laakso, T. T. Heikkila, and Yuli V. Nazarov
We propose a mesoscopic setup which exhibits strong and manifestly non-Gaussian fluctuations of energy and temperature when suitably driven out of equilibrium. The setup consists of a normal metal island (N) coupled by tunnel junctions (I) to two superconducting leads (S), forming a SINIS structure, ... [Phys. Rev. Lett. 108, 067002 ] published .
Avoidance of Majorana Resonances in Periodic Topological Superconductor-Nanowire Structures
Jay D. Sau, Chien Hung Lin, Hoi-Yin Hui, and S. Das Sarma
Semiconducting nanowires in proximity to superconductors are promising experimental systems for Majorana fermions which may ultimately be used as building blocks for topological quantum computers. A serious challenge in the experimental realization of the Majorana fermion in these semiconductor-supe ... [Phys. Rev. Lett. 108, 067001 ] published .
Velocity-induced reorientation of a fast driven Abrikosov lattice
S. Okuma, D. Shimamoto, and N. Kokubo
From mode-locking measurements where the vortex lattice is driven quickly by superimposed dc and ac currents, we find a velocity-induced rotation of lattice orientation from a perpendicular to a parallel orientation. This is a dynamic transition caused by increased velocity. At the threshold of the ... [Phys. Rev. B 85, 064508 ] published .
Ground-state phase diagram of the quantum JJ model on the honeycomb lattice
Fabio Mezzacapo and Massimo Boninsegni
We study the ground-state phase diagram of the quantum JJ model on the honeycomb lattice by means of an entangled-plaquette variational ansatz. Values of energy and relevant order parameters are computed in the range 0<=J/J<=1. The system displays classical order for J/J<~0.2 (Neel) and for J/J>~0.4 ... [Phys. Rev. B 85, 060402 ] published .
Synthesis, microstructure and magnetic properties of low Nd content FeNdBM (M = Hf, Ti and Ta) alloys
Zeqiang Zhang, Parmanand Sharma, Kunio Yubuta, and Akihiro Makino
We have investigated the effects of Hf, Ti and Ta addition on crystallization behavior, microstructure and magnetic properties of melt-spun FeNdBM (M = Hf, Ti and Ta) alloy ribbons. Optimization of processing conditions lead to the development of nano-composite magnets, made from high B soft magneti ... [J. Appl. Phys. 111, 07B501 (2012)] published Wed Feb 8, 2012.
Condition of the ratchet effect of a magnetic domain wall motion under an asymmetric potential energy
Hong-Guang Piao, Xiaozhong Zhang, Hyeok-Cheol Choi, Dong-Hyun Kim, and Chun-Yeol You
We have investigated the ratchet effect of magnetic domain wall (DW) motion in a straight ferromagnetic nanowire under ac magnetic field by means of micromagnetic simulation. A structure-stable DW ratchet effect along the ferromagnetic nanowire is observed utilizing an asymmetric potential produced ... [J. Appl. Phys. 111, 07D301 (2012)] published Wed Feb 8, 2012.
Spin reorientation transition and hard magnetic properties of MnBi intermetallic compound
K. Suzuki, X. Wu, V. Ly, T. Shoji, A. Kato et al.
The effects of mechanical grinding (MG) on the crystallite size, the spin reorientation transition temperature (T) and the hard magnetic properties in melt-spun low temperature phase (LTP) MnBi have been investigated in order to understand the origin of magnetic hardening induced by MG. The room-tem ... [J. Appl. Phys. 111, 07E303 (2012)] published Wed Feb 8, 2012.
Random magnetization dynamics at elevated temperatures
I. Mayergoyz, G. Bertotti, C. Serpico, Z. Liu, and A. Lee
Generalization of the classical Landau-Lifshitz equation for the case of magnetization dynamics at elevated temperatures is discussed. This generalization is based on the description of thermal bath effects by a jump-noise process, and it results in equations that describe magnetization dynamics whe ... [J. Appl. Phys. 111, 07D501 (2012)] published Wed Feb 8, 2012.
Non-collinear magnetic profile in (Rh/FeCo)/Rh(001) bilayer probed by polarized soft x-ray resonant magnetic reflectivity
M. Przybylski, J.-M. Tonnerre, F. Yildiz, H. C. N. Tolentino, and J. Kirschner
Magnetization configuration in Fe/Rh/FeCo/Rh(001) can be non-orthogonal due to competition between the anisotropy and the exchange coupling. Soft x-ray resonant magnetic reflectivity allows us to probe the magnetic profile along the growth axis with in-plane and perpendicular magnetization component ... [J. Appl. Phys. 111, 07C103 (2012)] published Wed Feb 8, 2012.
Electronic and magnetic properties of substitutionally Fe-, Co-, and Ni-doped BC honeycomb structure
Xianqing Lin and Jun Ni
First-principles calculations have been performed to investigate the electronic and magnetic properties of BC honeycomb structure (2D BC) substitutionally doped with Fe, Co, and Ni. 2D BC is a semiconductor with a mediate bandgap. When substituting for B, the Fe, Co, and Ni impurity atoms exhibit di ... [J. Appl. Phys. 111, 034309 (2012)] published Wed Feb 8, 2012.
Ab initio investigations of phonons and superconductivity in the cubic Laves structures LaAl and YAl
S. Duman and H. M. Tutuncu
We have performed an ab initio study of structural, elastic, electronic, lattice-dynamical, and electron-phonon interaction properties of the cubic Laves structures LaAl and YAl. The calculations have been carried out within the density-functional theory and linear response formalism using pseudopot ... [J. Appl. Phys. 111, 033514 (2012)] published Wed Feb 8, 2012.
Asymmetric switching behavior in perpendicularly magnetized spin-valve nanopillars due to the polarizer dipole field
D. B. Gopman, D. Bedau, S. Mangin, C. H. Lambert, E. E. Fullerton et al.
We report the free layer switching field distributions of spin-valve nanopillars with perpendicular magnetization. While the distributions are consistent with a thermal activation model, they show a strong asymmetry between the parallel to antiparallel and the reverse transition, with energy barrier ... [Appl. Phys. Lett. 100, 062404 (2012)] published Wed Feb 8, 2012.
Semiclassical theory of magnetoresistance in positionally disordered organic semiconductors
N. J. Harmon and M. E. Flatte
A recently introduced percolative theory of unipolar organic magnetoresistance is generalized by treating the hyperfine interaction semiclassically for an arbitrary hopping rate. Compact analytic results for the magnetoresistance are achievable when carrier hopping occurs much more frequently than t ... [Phys. Rev. B 85, 075204 ] published .
Magnetic field dependence of the quantum tunneling of normal-superconductor interfaces in a type-I Pb superconductor
Saul Velez, Ricardo Zarzuela, Antoni Garcia-Santiago, and Javier Tejada
We report experimental evidence of the effect of an applied magnetic field on the nonthermal magnetic relaxation in a disk-shaped type-I lead superconductor. The time evolution of the irreversible magnetization proves to be logarithmic for a wide range of temperatures and magnetic field values along ... [Phys. Rev. B 85, 064506 ] published .
Domain structure and magnetic pinning in ferromagnetic/superconducting hybrids
V. Vlasko-Vlasov, A. Buzdin, A. Melnikov, U. Welp, D. Rosenmann et al.
Magnetic patterns in three iron-garnet films with different magnetic properties covered with 100-nm superconducting Nb film are studied using a magneto-optical imaging technique. In all samples the strong coupling between ferromagnetic domains and vortices noticeably modifies the magnetization proce ... [Phys. Rev. B 85, 064505 ] published .
Effects of magnetic field, anisotropy, and biquadratic interactions in type-IIA fcc antiferromagnets studied by linear spin-wave theory
Trinanjan Datta and Dao-Xin Yao
We study the spin dynamics in a 3D quantum antiferromagnet on a face-centered-cubic (fcc) lattice. The effects of magnetic field, single-ion anisotropy, and biquadratic interactions are investigated using linear spin-wave theory with spins in a canted basis about the type-IIA fcc antiferromagnetic g ... [Phys. Rev. B 85, 054409 ] published .
Critical temperature and correlation length of an elastic interaction model for spin-crossover materials
Taro Nakada, Takashi Mori, Seiji Miyashita, Masamichi Nishino, Synge Todo et al.
It has previously been pointed out that the coexistence of infinite-range and short-range interactions causes a system to have a phase transition of the mean-field universality class, in which the cluster size is finite even at the critical point. In the present paper, we study this property in a mo ... [Phys. Rev. B 85, 054408 ] published .
First-principles study of structural, magnetic, and electronic properties of small Fe-Rh alloy clusters
Junais Habeeb Mokkath and G. M. Pastor
The structural, electronic, and magnetic properties of small FeRh clusters having N=m+n<=8 atoms are studied in the framework of a generalized-gradient approximation to density-functional theory. For N=m+n<=6, a thorough sampling of all cluster topologies has been performed, while for N=7 and 8, onl ... [Phys. Rev. B 85, 054407 ] published .
Suppression of edge magnetism in a titanium-embedded zigzag graphene nanoribbon
Yu Guodong, Lu Xiaoling, Zheng Yisong, and Tian Wenjing
Electronic and magnetic properties of zigzag-edged graphene nanoribbons (ZGNR) embedded with titanium (Ti) atoms are studied by means of the first principle calculations. When Ti atoms are positioned near either edge of the ZGNR, the magnetic moment at this edge is rapidly suppressed as the Ti conce ... [J. Appl. Phys. 111, 033707 (2012)] published Tue Feb 7, 2012.
Thickness-dependent evolution of magnetization reversal in micron-scale polycrystalline Fe rings
Yu-feng Hou and Kannan M. Krishnan
The evolution of magnetic switching mechanism is investigated for micron-scale polycrystalline Fe ring arrays with Fe layer thickness, t, varying between 10 nm and 50 nm. Single-step and double-step switching are observed for the 10 nm and 50 nm rings, with the 30 nm sample showing a transient behav ... [J. Appl. Phys. 111, 033910 (2012)] published Tue Feb 7, 2012.
Emergent magnetic monopoles, disorder, and avalanches in artificial kagome spin ice (invited)
R. V. Hugli, G. Duff, B. O'Conchuir, E. Mengotti, L. J. Heyderman et al.
We study artificial spin ice with isolated elongated nanoscale islands arranged in a kagome lattice and solely interacting via long range dipolar fields. The artificial kagome spin ice displays a phenomenology similar to the microscopic pyrochlore system, where excitations at sub-Kelvin temperatures ... [J. Appl. Phys. 111, 07E103 (2012)] published Tue Feb 7, 2012.
Electron resonance and magnetic response of low-doped LaCaMnO and LaSrMnO manganite single crystals
E. Rozenberg, A. I. Shames, M. I. Tsindlekht, I. Felner, and Ya. M. Mukovskii
Ferromagnetic resonance and ac/dc magnetic properties of the low-doped LaCaMnO and LaSrMnO manganite single crystals were studied below (down to 5 K) their paramagnetic-ferromagnetic phase transition. It appears that technologically driven chemical/structural disorder inherent to low-doped manganite ... [J. Appl. Phys. 111, 07D702 (2012)] published Tue Feb 7, 2012.
Scaling fit of spin pumping in various ferromagnetic materials
T. Yoshino, K. Ando, Y. Kajiwara, H. Nakayama, and E. Saitoh
In this paper, we have investigated spin currents generated by the spin pumping in ferromagnetic metal/Pt and ferromagnetic insulator/Pt bilayer films using the inverse spin-Hall effect (ISHE). We found that the magnitude of the electric voltage due to the ISHE is well reproduced by a calculation ba ... [J. Appl. Phys. 111, 07C502 (2012)] published Tue Feb 7, 2012.
1s2p resonant inelastic x-ray scattering-magnetic circular dichroism: A sensitive probe of 3d magnetic moments using hard x-ray photons
M. Sikora, A. Juhin, G. Simon, M. Zajac, K. Biernacka et al.
We investigated the magnetic properties of thin magnetite and iron films grown on MgO(001) by means of hard x-ray photon-in photon-out probe, namely, 1s2p resonant inelastic x-ray scattering-magnetic circular dichroism (RIXS-MCD). A comparison of the spectra acquired from bulk and thin layer magneti ... [J. Appl. Phys. 111, 07E301 (2012)] published Tue Feb 7, 2012.
The compressive stress effect on the magnetostriction and magnetization for Sm-Dy-Fe composites
Bowen Wang, Zhihua Wang, Yanming Hao, Ling Weng, Wenmei Huang et al.
SmDyFe rod composites were fabricated under a compaction pressure of 800 MPa along the rod direction and in a magnetic field of 200 kA/m along the direction, perpendicular to the rod axis. It is found that the magnetostriction lambda parallel to the rod direction is almost unchanged with increasing ... [J. Appl. Phys. 111, 07A906 (2012)] published Tue Feb 7, 2012.
Oscillatory magnetic anisotropy due to quantum well states in thin ferromagnetic films (invited)
M. Przybylski, M. Dabrowski, U. Bauer, M. Cinal, and J. Kirschner
Magnetic anisotropy depends strongly on the density of states at the Fermi level. If significant contributions to magnetocrystalline anisotropy energy (MAE) are due to spin-polarized quantum well states (QWS), a significant increase of MAE can occur periodically as a function of film thickness. The ... [J. Appl. Phys. 111, 07C102 (2012)] published Tue Feb 7, 2012.
Domain structure and magnetization loss in a toroidal core based on an Fe-based amorphous alloy
Daichi Azuma, Ryusuke Hasegawa, Shin Saito, and Migaku Takahashi
By utilizing a wide-view Kerr-effect magnetic domain observation system designed for domain observation on curved surfaces, domain images were taken on the surface of a toroidal core based on an Fe-based amorphous alloy. The results of the observation are discussed in terms of Bertotti's eddy-curren ... [J. Appl. Phys. 111, 07A302 (2012)] published Tue Feb 7, 2012.
Magnetic characteristics of a new cubic defect spinel LiMgMnO
V. Singh, M. S. Seehra, A. Manivannan, and P. N. Kumta
Magnetic properties of LiMgMnO nanoparticles (size ~= 20 nm) synthesized by the Pechini method are investigated using temperature dependence of its magnetization (M) and electron magnetic resonance (EMR) spectra at 9.286 GHz. Analysis of the x-ray diffraction spectra yields its structure to be a cub ... [J. Appl. Phys. 111, 07E302 (2012)] published Tue Feb 7, 2012.
Behavior of magnetic fieldannealed Galfenol steel
Michael Brooks, Eric Summers, J. B. Restorff, and M. Wun-Fogle
An attractive feature of the Galfenol alloy system is the ability to impart enough uniaxial anisotropy into the alloy such that no pre-load mechanism is required to attain saturation magnetostriction. Stress annealing is typically employed to generate this anisotropy. Recent published results indica ... [J. Appl. Phys. 111, 07A907 (2012)] published Tue Feb 7, 2012.
Broadband ferromagnetic resonance spectroscopy of permalloy triangular nanorings
J. Ding, M. Kostylev, and A. O. Adeyeye
We investigate the spin dynamics in triangular shaped permalloy rings using broadband ferromagnetic resonance spectroscopy. Compared with circular rings, we observed multiple resonance frequency peaks, which are strongly dependent on the orientation of the applied magnetic field relative to the hori ... [Appl. Phys. Lett. 100, 062401 (2012)] published Tue Feb 7, 2012.
Giant Improper Ferroelectricity in the Ferroaxial Magnet CaMnO
R. D. Johnson, L. C. Chapon, D. D. Khalyavin, P. Manuel, P. G. Radaelli et al.
In rhombohedral CaMnO, an improper ferroelectric polarization of magnitude 2870 [mu]C m is induced by an incommensurate helical magnetic structure that evolves below T=90 K. The electric polarization was found to be constrained to the high symmetry threefold rotation axis of the crystal structure ... [Phys. Rev. Lett. 108, 067201 ] published .
Triviality problem and high-temperature expansions of higher susceptibilities for the Ising and scalar-field models in four-, five-, and six-dimensional lattices
P. Butera and M. Pernici
High-temperature expansions are presently the only viable approach to the numerical calculation of the higher susceptibilities for the spin and the scalar-field models on high-dimensional lattices. The critical amplitudes of these quantities enter into a sequence of universal amplitude ratios that d ... [Phys. Rev. E 85, 021105 ] published .
Coexisting pseudogap, charge-transfer-gap, and Mott-gap energy scales in the resonant inelastic x-ray scattering spectra of electron-doped cuprate superconductors
Susmita Basak, Tanmoy Das, Hsin Lin, M. Z. Hasan, R. S. Markiewicz et al.
We present a computation of Cu K-edge resonant inelastic x-ray scattering (RIXS) spectra for electron-doped cuprates, which includes coupling to bosonic fluctuations. Comparison with experiment over a wide range of energy and momentum transfers allows us to identify the signatures of three key norma ... [Phys. Rev. B 85, 075104 ] published .
Publisher's Note: BT phase diagram of CoCrO in magnetic fields up to 14 T [Phys. Rev. B 85, 012101 (2012)]
A. V. Pronin, M. Uhlarz, R. Beyer, T. Fischer, J. Wosnitza et al.
Abstract not available. [Phys. Rev. B 85, 069901 ] published .
Structure of the oxygen-annealed chalcogenide superconductor FeTeSeO
Hefei Hu, Jian-Min Zuo, Mao Zheng, James N. Eckstein, Wan Kyu Park et al.
The as-grown single crystal FeTeSe with the tetragonal PbO-type structure is nonsuperconducting owing to the excess Fe. Superconductivity is induced after oxygen annealing with an onset and zero resistance transition temperature around 14.5 K and 11.5 K, respectively. The oxygen doping is evidenced ... [Phys. Rev. B 85, 064504 ] published .