High-mobility InAs heterostructure meets criteria for topological superconductivity regime

Superconducting quantum computing and the realization of topological states of matter require materials with a controllable proximity effect, the phenomena that occur when a superconductor contacts a nonsuperconductor. Potential suitable materials include two-dimensional electron systems confined to surface layers of indium arsenide, InAs. InAs requires more study, as it’s one of the few materials that can interface well with metals and superconductors, unlike silicon and gallium arsenide.

Using a two-dimensional electron system confined in InAs surface, Wickramasinghe et al. developed a heterostructure and studied the magnetotransport properties of its near-surface InAs quantum wells. Measuring magnetotransport as a function of top-barrier thickness and doping density, they found that top-layer thickness and ionized impurity scattering both affect the mobility of the structure. They also clearly observed well-developed integer quantum Hall states for the first time.

From their measurements, the authors concluded that the two-dimensional electron system confined to indium arsenide layers provides a semiconducting platform with higher mobility than previously reported. This heterostructure also demonstrates a clean interface with superconducting materials, a strong spin orbit coupling and a gate-controllable electron density, permitting the study of exotic states in the proximity of superconductors.

These characteristics imply that the proximity effect of the heterostructure can be tuned when it’s coupled with a superconductor. Javad Shabani said that this heterostructure can serve as a platform for engineering topological phases of matter and, more generally, mesoscopic superconductivity.

Source: “Transport properties of near surface InAs two-dimensional heterostructures,” by Kaushini S. Wickramasinghe, William Mayer, Joseph Yuan, Tri Nguyen, Lucy Jiao, Vladimir Manucharyan, and Javad Shabani, Applied Physics Letters (2018). The article can be accessed at https://doi.org/10.1063/1.5050413 .