Large and anisotropic zero-field spin-splittings in InxGa1−xAs/InyAl1−yAs (x,y>0.6) heterojunctions

Abstract

Large and in-plane anisotropic zero-field spin-splittings are found in two-dimensional electron gas (2DEG) formed at InxGa1−xAs/InyAl1−yAs (x,y>0.6) heterojunctions. Low-temperature magnetoresistance (MR) measurements were carried out in van der Pauw, Hall bar and quantum wire field effect transistor (QWR-FET) samples. Maximum spin–orbit coupling constant αzero of 78(×10−12eVm) was attained at 1.5 K in the Hall bar sample with the 〈−110〉 direction. Also, an in-plane anisotropy of almost twice as well as a gate-voltage-dependent change of αzero are confirmed in QWR-FET samples with 〈−110〉 and 〈110〉 directions. Those results suggest the importance of interface contribution to the zero-field spin splitting, which might be enhanced in our unique heterojunctions.