Electronic Liquid Crystals

Steve Kivelson, Professor of Physics, Stanford University

The remarkable stability of the Fermi liquid state is responsible for the notably limited variety of ordered states seen in weakly interacting electron fluids, i.e., "good metals." In highly correlated electron fluids, by contrast, theoretical "proofs of principle" have been constructed in the past decade, for a rich
variety of broken symmetry, topologically ordered, and otherwise distinct new quantum states of matter.

Moreover, in the past several years, the existence in real materials of several such phases has been established by careful, focussed, and laborious experimental effort. In this talk I will discuss a class of "novel" electronic states which exhibit broken symmetries reminiscent of certain liquid crystalline phases that occur in classical complex fluids. As a principle example, I will discuss the electron nematic phases that have been seen in highly ordered semiconducting heterostructures and in crystals of several transition metal oxides.

I will also briefly discuss the experimental discovery and tentative theoretical understanding of a novel "striped superconductor," a phase which, in a highly uniform three dimensional bulk crystal, exhibits a form of "dynamical dimensional reduction." Specifically, at low temperatures, the resistance anisotropy begins to grow explosively with decreasing temperature until, below a critical temperature, it becomes infinite within experimental uncertainty, in the sense that the crystal is apparently superconducting in two dimensions, while being barely metallic in the third.