Interacting two-dimensional electron and hole systems in perpendicular magnetic fields

Tue, Mar 2, 2021, 1:30 pm to 3:00 pm


Electron and hole systems confined in two dimensions (2D) exhibit a plethora of exotic quantum phases under perpendicular magnetic fields at sufficiently low temperatures (milli-Kelvin range). The work presented here explores two of these quantum phases in state-of-the-art high-quality GaAs and InAs quantum wells.

The first quantum phase studied is called the Wigner solid (WS) phase, in which the charged carriers organize themselves in a periodic array. The magnetic-field-induced WS phase forms when the 2D system is under a sufficiently large perpendicular magnetic field at very low temperature, where the kinetic (Fermi) energy is quenched, and the Coulomb repulsion energy dominates. In the first part of my talk, I will present the thermal and quantum melting phase diagrams of the magnetic-field-induced WS phases residing in a high-quality GaAs 2D hole system. We find our data to be in good agreement with the results of very recent calculations, although intriguing subtleties remain.

The second quantum phase studied is the fractional quantum Hall state. We observed the nu=4/3 fractional quantum Hall state in a high-quality InAs quantum well—a quantum state formed due to electron-electron interaction. This is of interest because the 2D electron system in an InAs quantum well has emerged as a prime candidate for hosting exotic quasi-particles with non-abelian statistics such as Majorana fermions and parafermions which could find use in the realization of topological quantum computing. To attain its full promise, however, the electron system has to be clean enough to exhibit electron-electron interaction phenomena.

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