Atomic-layer deposition process enables easier fabrication of spintronic devices

Spintronics has revolutionized the information-storage industry, but current fabrication methods are highly constrained and optimized, which limits the spintronics architectures that can be created. Quinard et al. reported a simple, low-cost, and conformal method to fabricate a working spin source.

The method is a simple atomic-layer deposition (ALD) process that uses limited temperature and millibars of pressure to grow a known ferromagnetic cobalt spin source onto a substrate. They found the cobalt retained its spintronics qualities with relaxed ALD growth conditions even though ferromagnets typically lose their spintronics properties quickly when exposed to the oxidation from air.

“Our result is the first step to exploit ALD unique properties (such as atomic control of thicknesses and 3D conformality) to engineer novel spin architectures beyond the reach of usual spintronics physical vapor deposition approaches,” author Bruno Dlubak said.

To construct their devices, the authors used a custom fabrication tool to integrate the ALD-grown cobalt spin sources in-situ with ultra-thin oxide layers used as tunnel barriers. This step was necessary to retain the spintronics properties of the surface of the cobalt. To characterize the ALD grown cobalt spin sources, the team carried out a wide range of morphological, chemical, and magnetic analysis, then integrated the cobalt into a spintronics device called a spin valve to validate it was indeed a working spintronic electrode.

The authors believe this work is important because ALD, a technique already successfully used in the microelectronics industry, can help realize previously unreachable architectures.

“Many systems of spintronics, such as other ferromagnets and alloys, and complex functional heterostructures seem now at hand by the ALD approach,” Dlubak said.

Source: “A ferromagnetic spin source grown by atomic layer deposition,” by B. Quinard, F. Godel, M. Galbiati, V. Zatko, A. Sander, A. Vecchiola, S. Collin, K. Bouzehouane, F. Petroff, R. Mattana, M.-B. Martin, B. Dlubak, and P. Seneor, Applied Physics Letters (2021). The article can be accessed at https://doi.org/10.1063/5.0087869 .