Magnetically Controllable Two‐Dimensional Spin Transport in a 3D Crystal

Abstract 2D phases of matter have become a new paradigm in condensed matter physics, bringing in an abundance of novel quantum phenomena with promising device applications. However, realizing such quantum phases has its own challenges, stimulating research into non‐traditional methods to create them. One such attempt is presented here, where the intrinsic crystal anisotropy in a “fractional” perovskite, Eu x TaO 3 ( x = 1/3 − 1/2), leads to the formation of stacked layers of quasi‐2D electron gases, despite being a 3D bulk system. These carriers possess topologically non‐trivial spin textures, indirectly controlled by an external magnetic field via proximity effect, making it an ideal system for spintronics, for which several possible applications are proposed. An anomalous Hall effect with a non‐monotonic dependence on carrier density is shown to exist, signifying a shift in band topology with carrier doping. Furthermore, quantum oscillations in charge conductivity and oscillating thermoelectric properties are examined and proposed as routes to experimentally demonstrate the quasi‐2D behavior.