Speaker: Aryan Navabi
Affiliation: Ph.D. Candidate - UCLA
Abstract: Spin-waves are coherent oscillations of magnetic moments and can propagate in ferromagnetic materials. These magnetic oscillations are similar to ferromagnetic resonance and can be used in RF components such as tunable YIG filters. Planar YIG films can be integrated with integrated circuits to realize devices such as frequency selective limiters and signal to noise enhancers. However, such films suffer from spin-wave damping which results in high insertion losses. This limits their use in RF/Microwave applications.
In this talk, I will demonstrate reduction of spin-wave damping using spin currents from Topological Insulators (TI). TI supports spin-polarized currents localized at its surfaces, potentially making it an efficient source of anti-damping torque. We show that in an YIG/Bi2Se3 bilayer, the spin-wave damping rate can be reduced by 60% using current pulses with a density of 8×105 A/cm2. Furthermore, we show that the damping reduction has a strong dependence on spin-wave frequency, and we demonstrate that this dependence arises from nonlinear magnons scattering. Finally, I will demonstrate our recent results where we show that the insertion loss can be reduced using a continuous supply of current in an YIG/Bi2(SbTe)3 bilayer using the spin Seebeck effect.
Biography: Aryan Navabi received his Bachelor in Applied Science in Electrical Engineering in 2010 from University of British Columbia in the Microsystems and Nanotechnology track (mina.ubc.ca). During his undergraduate studies, he volunteered in research groups and worked on different areas such as sensors and quantum-dot cellular automata. After receiving his B.A.Sc., he worked on 2D materials at the Quantum Devices Group in the Physics and Astronomy Department as a researcher under a research award from the Natural Sciences and Engineering Research Council of Canada (NSERC). He joined UCLA in September 2011 as a Master’s student. For his PhD, Aryan has worked on spin-waves for high-frequency applications and integration of topological insulators with YIG for RF components such as frequency selective limiters.
Date(s) - Apr 10, 2018
2:00 pm - 4:00 pm
E-IV Tesla Room #53-125
420 Westwood Plaza - 5th Flr., Los Angeles CA 90095