Possible nematic to smectic phase transition in a two-dimensional electron gas at half-filling

Area of Science:

• Condensed matter physics
• Materials science

Background:

• Liquid crystalline phases are ubiquitous in nature and technology.
• Electronic liquid-crystal phases have been observed in two-dimensional electron systems (2DES) at half Landau-level filling within the quantum Hall regime.
• Theoretical models predict a smectic phase breaking rotational and translational symmetries, but experimental evidence has favored an anisotropic nematic phase.

Purpose of the Study:

• To investigate the electronic liquid-crystalline phases in ultra-low disorder 2DES at half-filling.
• To identify the specific symmetry-breaking transitions occurring as temperature is reduced.
• To provide experimental evidence for the existence of the predicted smectic phase.

Main Methods:

• Transport measurements in ultra-low disorder 2DES at half-filling.
• Analysis of sample resistance dependence on temperature.
• Observation of resistance fluctuations and differential resistance features.

Main Results:

• Observed a non-monotonic temperature dependence of sample resistance.
• Detected the onset of significant time-dependent resistance fluctuations.
• Identified a sharp feature in differential resistance indicative of depinning.

Conclusions:

• The experimental data suggest a sequence of phase transitions as temperature decreases.
• These transitions include a shift from an isotropic liquid to a nematic phase, followed by a transition to a liquid-crystal smectic phase.
• The findings provide strong evidence for the existence of the smectic phase in 2DES.