Hints of Electronic Nematicity at the (111) LaAlO₃/SrTiO₃ Interface

The two-dimensional conducting electron gas (2DCG) that forms at the interface between the two band insulators LaAlO₃ (LAO) and SrTiO₃ (STO) has been extensively studied due to the wealth of in-situ tunable phenomena that exist at the interface. We have shown that nearly every property of the 2DCG that forms at the interface of (111) oriented LAO/STO is strongly anisotropic with respect to in-plane crystal direction. This symmetry breaking points to the existence of an electronic nematic phase at the interface that can be modified by an in-situ electrostatic back gate potential. Here we show that the anisotropy turns on simultaneously in both the longitudinal resistance and Hall response at T ≈ 22 K, which does not match up with any known structural transition. Furthermore, below 22 K, charge transport is activated with different activation energies along the two in-plane crystal directions. This response implies that the band edges along the two directions are different giving further evidence of an electronic nematic state at the interface.

S. Davis et al., arXiv:1708.04809 (2017)