Spin-Orbitronics: A Route to Control Magnets via Spin-Orbit Interaction
|Event Date:||July 6, 2017|
|Speaker:||Dr. Pramey Upadhyaya|
|Contact Name:||Professor Supriyo Datta
|School or Program:||Electrical and Computer Engineering
Relativistic effects, having far reaching consequences for advancing our fundamental understanding of the nature, have so far mostly played an academic role in solid-state systems. For example, electrons moving in atomic orbitals close to the speed of light acquire a relativistic shift in energy via the so-called spin-orbit interaction (SOI). More recently, the ability to engineer this SOI in magnetic systems has shown potential to extend the reach of relativity into information processing by providing a universal energy-efficient knob to control magnetic order via electrical, thermal, mechanical and optical means. In this talk, I will present this “spin-orbitronic” control for various magnetic systems. In particular, we will focus on the example of spin-orbit-induced manipulation of magnetic domain walls and skyrmions, i.e. particle-like magnetic configurations capable of storing and transporting non-volatile information. Firstly, we will present a strategy to create, move and guide skyrmions electrically at room temperature. Secondly, motivated by lowering the energy dissipated as Joule heating, we theoretically demonstrate the possibility of manipulating domain walls by spin currents transported via dissipation-free channels in spin superfluids and chiral edge states of magnetically-doped topological insulators. Thirdly, we will present domain-wall motion in an all-insulating system via SOI-enabled transfer of angular momentum from fluctuations of magnetic order in the presence of thermal gradients. This transfer, which we refer to as local thermomagnonic torque, may thus provide a pathway to either eliminate or harvest thermal energy dissipated via Joule heating. Finally, we demonstrate how single spin states in Nitrogen vacancy center in diamond act as nanoscale probes to measure these local thermomagnonic torques.
Pramey Upadhyaya is a postdoctoral scholar in the Physics and Astronomy department, University of California Los Angeles. He earned his bachelor’s degree in Electrical Engineering from the Indian Institute of Technology Kharagpur, India, in 2009, and the master’s and Ph.D. degree in Electrical Engineering department from the University of California Los Angeles, USA, in 2011 and 2015, respectively. His research has explored theory of classical and quantum spintronic phenomenon, and their device applications, enabled by electrical and thermal control of magnetism. He is a recipient of Director’s fellowship from the Los Alamos National Laboratory (2017), Qualcomm Innovation fellowship (2013) and Intel summer fellowship (2011).