Utilizing Valley-Spin Hall Effect in WSe2 for Low Power Non-Volatile Flip-Flop Design

Abstract

By virtue of the broken inversion symmetry and preserved time-reversal symmetry in monolayer WSe 2 , electrons from K and K’ valleys exhibit opposite spins [1] . Thus, when charge current ( I C ) flows, transverse spin currents ( I S ) are generated perpendicular to I C with up/down spins ( I S↑ /I S↓ ) flowing in opposite directions due to valley-spin hall effect (VSHE) [1] , [2] ( Fig. 1(a) ). The generated spins are out-of-plane and can be coupled with ferromagnets (FMs) with perpendicular magnetic anisotropy (PMA) to control their magnetizations [2] . Hence, magnetization switching energy can potentially be reduced compared to Giant Spin Hall Effect (GSHE) based switching of FMs with in-plane magnetic anisotropy (IMA) [3] . To effectively harness VSHE for circuit applications, careful device-circuit co-design is needed.