Surface Spin Polarization in the Magnetic Response of GeTe Rashba Ferroelectric

Abstract

We experimentally investigate magnetization reversal curves for a GeTe topological semimetal. In addition to the known lattice diamagnetic response, we observe narrow magnetization loop in low fields, which should not be expected for non-magnetic material. The diamagnetic hysteresis loop is unusual, so the saturation level is negative in positive fields, and the loop is passed clockwise, in contrast to standard ferromagnetic behavior. We show, that the experimental hysteresis curves can not be obtained from standard ferromagnetic ones by adding/subtracting of any linear dependence, or even by considering several interacting magnetic phases. The latter possibility is also eliminated by the remanence plots technique (Henkel or δM plots). We explain our results as a direct consequence of the correlation between ferroelectricity and spin-polarized surface states in GeTe, similarly to magnetoelectric structures.