Spintronics based on Novel Topological Materials

Seminar
Wednesday, April 12, 2017
10:00 AM to 11:00 PM
POB 2.302
Free and open to the public

Magnetic spintronic devices are a promising research direction for the implementation of non-volatile memory and logic technologies with fast speed, high density, reliable performance and low power consumption. In particular, novel materials have been incorporated in the magnetic structures to realize manipulation and/or switch of magnetization with the least possible current and power. Among them, topological insulators (TIs), which exhibit strong spin-orbit coupling and nontrivial band topology, have been employed to generate spin-orbit torques (SOTs) to enable efficient switching of the magnetic moment. In this presentation, we will first show the magnetization switching through giant SOT in a TI/Cr-doped TI bilayer structure. The critical current density required for switching is below A/cm2. The SOT efficiency in this bilayer is found to be three orders of magnitude larger than those reported for conventional heavy metal/ferromagnet heterostructures. Second, we will present the effective electric-field control of the giant SOT in a uniformly Cr-doped TI thin film using a top-gated field-effect transistor structure. We will show that the SOT can be modulated by a factor of 4 within the accessible gate voltage range. Furthermore, we demonstrate that the magnetization can be switched by scanning gate voltage, which suggests promising gate-controlled spin-torque device applications. Lastly, we will discuss the future potential research opportunities in this topological spintronics research field, considering the many new topological materials that have been discovered, such as the topological semimetals and nontrivial 2-dimensional materials with strong spin-orbit coupling. The giant SOT and efficient current-induced magnetization switching exhibited by the magnetic TI materials suggest that novel topological materials may find wide applications in the next-generation ultralow power consumption memory and logic devices.

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Speaker

Yabin Fan

Yabin Fan

Postdoctoral Scholar
University of California, Los Angeles

Yabin Fan is currently a postdoctoral researcher in the Device Research Laboratory (DRL) of the Electrical Engineering Department at University of California, Los Angeles (UCLA), under the mentorship of Prof. Kang L. Wang. He obtained the M.S. degree in 2012 and the Ph.D. degree in 2016, both in the Electrical Engineering Department at UCLA. His research focuses on spintronics devices based on topological materials, such as the current-induced giant spin-orbit torque in topological insulator-based magnetic structures, quantum anomalous Hall effect in magnetic topological insulators, and various spin-orbit torque phenomena in topological materials with strong spin-orbit coupling. He is a member of the American Physical Society (APS). During his graduate research, he has authored and co-authored over 30 journal papers. In addition, he has received the Best Student Presentation Finalist Award in the 59th Magnetism and Magnetic Materials (MMM) annual conference in 2014 and the Chinese Government Award for Outstanding Graduate Students Abroad in 2015.