Nematicity driven by superconducting correlations: Application to (111) KTaO3 interface 2DEG.

Recent experiments have discovered nematic transport and superconductivity in the two-dimensional electron gas (2DEG) at the (111) KTaO3 oxide interface. Motivated by these observations, a k.p model for the 2DEG was proposed and shown to exhibit a Z3 nematic instability due to electron interactions. We argue that such an instability might lead to the formation of nematogens - mesoscopic domains with local nematicity but no global nematic order. When superconducting fluctuations are coupled to these nematogens, we show using Landau theory and Monte Carlo simulations that the directional delocalization of Cooper pairs favors global symmetry breaking. Using a resistor network calculation, we show that such a system shows strong transport anisotropy below a temperature which is closely tied to the superconducting fluctuations. We qualitatively discuss the impact of disorder, residual strains, and magnetic field induced frustration of nematic order. Our results qualitatively explain many of the observations on the (111) KTaO3 interface 2DEG, and may be generalized to other superconducting systems such as Cu/Nb doped topological insulator Bi2Se3.