APS -APS March Meeting 2017 - Event - Quasiparticle spin relaxation with superconducting-velocity--tunable state in GaAs (100) quantum wells in proximity to $s$-wave superconductor

摘要

We investigate the quasiparticle spin relaxation withsuperconducting-velocity--tunable state in GaAs (100) quantum wells in proximity to $s$-wave superconductor.In the quasiparticle state, rich features such as the suppressed Cooperpairings, large quasiparticledensity and non-monotonically tunable momentum current can be realized byvarying the superconductingvelocity. In the degenerate regime,the quasiparticle Fermi surface is composed by two arcs, referred to as Fermi arcs, whichare contributed by the electron- andhole-like branches. The D'yakonov-Perel' spin relaxation is explored with intriguing physics revealedwhen the Fermi arc emerges. Specifically, when the order parameter tends to zero, the branch-mixingscattering is forbidden.The open structure of the Fermi arc leads to the nonzero angular-averageof the effective magnetic field due to the spin-orbit coupling, acting asan effective Zeeman field. This Zeeman field leads to the spin oscillationseven in the strong scattering regime. Moreover, in the strong scatteringregime, the openstructure of the Fermi arc leads to the insensitiveness of the spinrelaxation to the momentum scattering, in contrast to the conventionalmotional narrowing situation.