Observation of field-induced polarization of valleys in p-type Sb2Te3 single crystals

A flow of carriers along the c axis is extremely sensitive to the orientation of an in-plane magnetic field due to in-plane mass anisotropy in layered compounds. Based on this mechanism, a rotatable in-plane magnetic field has been applied as a valley valve to tune the contribution of each valley in p-type Sb 2Te 3 bulk single crystals to the total conductivity and interlayer magnetoresistance (MR). A valley-polarized current is generated, and the angular-dependent interlayer MR of up to 160% represents strong anisotropy. There are six inequivalent peaks over all temperature and magnetic field ranges. The giant MR results from the intravalley and intervalley hole Coulomb scattering in upper valence bands. The interlayer MR anisotropy originates from field-induced polarization of valleys, and Coulomb interaction-induced valley distortion. The strong anisotropy of the angular-dependent interlayer MR reflects strong anisotropies of carrier scattering time and effective mass in the six valleys and their inequivalent contributions to total magnetoconductivity and interlayer MR in p-type Sb 2Te 3 bulk.