Liquid Crystal Phases of Quantum Hall Systems

TL;DR

This paper investigates the emergence of liquid crystalline phases, especially stripe-nematic states, in quantum Hall systems with high Landau level filling, supported by theoretical calculations and experimental evidence of anisotropic resistivity.

Contribution

It introduces a theoretical framework for understanding stripe-nematic phases in quantum Hall systems and links these phases to recent experimental observations of resistivity anisotropy.

Findings

Quantum and thermal fluctuations can stabilize stripe-nematic phases.

Experimental resistivity anisotropy supports the existence of stripe nematic states.

Proposed phase diagram for quantum Hall liquid crystalline phases.

Abstract

Mean-field calculations for the two dimensional electron gas (2DEG) in a large magnetic field with a partially filled Landau level with index $N\geq 2$ consistently yield ``stripe-ordered'' charge-density wave ground-states, for much the same reason that frustrated phase separation leads to stripe ordered states in doped Mott insulators. We have studied the effects of quantum and thermal fluctuations about such a state and show that they can lead to a set of electronic liquid crystalline states, particularly a stripe-nematic phase which is stable at $T>0$. Recent measurements of the longitudinal resistivity of a set of quantum Hall devices have revealed that these systems spontaneously develop, at low temepratures, a very large anisotropy. We interpret these experiments as evidence for a stripe nematic phase, and propose a general phase diagram for this system.