Temperature Dependent Symmetry to Asymmetry Transition in Wide Quantum Wells

TL;DR

This study investigates how temperature influences the transition from symmetric to asymmetric electron density profiles in wide quantum wells, revealing phase transitions relevant to quantum Hall states through self-consistent Schrödinger-Poisson calculations.

Contribution

It introduces a temperature-dependent analysis of density profile symmetry in wide quantum wells, highlighting the role of Coulomb interactions in phase transitions.

Findings

Density profiles change from symmetric to asymmetric with temperature.

Phase transitions are influenced by Coulomb interactions and material parameters.

Results impact understanding of quantum Hall states in wide quantum wells.

Abstract

Quasi-two dimensional electron systems exhibit peculiar transport effects depending on their density profiles and temperature. A usual two dimensional electron system is assumed to have a $\delta$ like density distribution along the crystal growth direction. However, once the confining quantum well is sufficiently large, this situation is changed and the density can no longer be assumed as a $\delta$ function. In addition, it is known that the density profile is not a single peaked function, instead can present more than one maxima, depending on the well width. In this work, the electron density distributions in the growth direction considering a variety of wide quantum wells are investigated as function of temperature. We show that, the double peak in the density profile varies from symmetric (similar peak height) to asymmetric while changing the temperature for particular growth parameters. The alternation from symmetric to asymmetric density profiles is known to exhibit intriguing phase transitions and is decisive in defining the properties of the ground state wavefunction in the presence of an external magnetic field, i.e from insulating phases to even denominator fractional quantum Hall states. Here, by solving the temperature and material dependent Schr\"odinger and Poisson equations self-consistently, we found that such a phase transition may elaborated by taking into account direct Coulomb interactions together with temperature.