Spintronics

There are alternatives for the next-generation computing technology such as quantum computing and spintronics. Spintronic devices are promsing owing to their low power consumption, high performance, and high compatibility to semiconductor VLSI technology . Among all spin-related technology, spin-based field-effect transistors (FET) are a promising candidate due to the similar operational principles to the state of the art logic device. To manipulate the spins in the channel, Rashba spin-orbit coupling (SOC) can be utilized to control the spin via the electric field. For common semiconductors, III-V family has strong Rashba SOC effects while for Si, the SOC strength is very weak. Recently, we observed strong SOC and ballistic spin transport in the two-dimensional electron hole gas (2DHG) formed on the Ge/GeSi heterostructures (featured in Nanoscale 2018, DOI), which makes a Si-compatible spin FET possible. Furthermore, we demonstrated the first 2DHG in the GeSn/Ge heterostructures with clear quantum Hall plateaus and Shubnikov-de Haas (SdH) oscillations.  We also observed very strong weak antilocalization (WAL) effects in the GeSn/Ge heterostructures (Advanced Materials 2021, DOI) and in bulk GeSn films (Journal of Applied Physics 2024, DOI). Combined with direct-bandgap characteristics for Si photonics and high carrier mobility for More-Moore's applications, GeSn is a very interesting and promising material to realize an all-in-one chip with electronic, optoelectronic, and spintronic functions.  Physics of group-IV heterostructures for quantum technologies and applications has been addressed in our review paper in Materials for Quantum Technology (2024, DOI).

In addition to GeSn, we are focusing on SOC effects in 2D materials such as graphene or MoS2. While most of TMD materials are predicted to have strong SOC effects, their poor transport limits the observation of SOC effects. Meanwhile, by proximity effect of TMD materials next to graphene, spin transport can be effectively probed.