Two-dimensional anisotropic Luttinger Liquids in a moiré superlattice

Fermi Liquid theory is the standard description for two and three-dimensional (2D and 3D) metals and the basis for understanding many quantum phenomena including the quantum Hall effect and superconductivity. 1D Luttinger Liquid (LL) state is one of the examples beyond the standard Fermi Liquid theory and involves strong electron correlations and fractionalized excitations. Substantial theoretical efforts have been made to expand the LL theory to higher dimensions, especially in the context of coupled-wire models consisting of an array of 1D LLs. However, the experimental test for the existence of a stable LL state in 2D or 3D is challenging due to the lack of a suitable material platform with high quality and tunability. In this talk, I will present our experimental search of a stable LL state in 2D based on moiré quantum engineering in small-angle twisted bilayer WTe₂ (tWTe₂) system. We find a new 2D anisotropic electronic phase akin to a LL, stabilized due to interactions in tWTe₂ moiré superlattice.  I will discuss three key transport characteristics of this phase, including (1) an exceptionally large in-plane transport anisotropy, (2) a power-law scaled conductance in the hard transport direction and (3) a nonlinear differential resistance, featuring a zero-bias dip, in the easy transport direction.