Thermal and quantum melting phase diagrams for a magnetic-field-induced Wigner solid

• Published in: arXiv.org 2020-06
• Main Authors: Ma, Meng K, Villegas Rosales, K A, Deng, H, Chung, Y J, Pfeiffer, L N, West, K W, Baldwin, K W, Winkler, R, Shayegan, M
• Format: Article
• Language: English
• Subjects: Energy conservation; Fermions; Heterostructures; Hole density; Low temperature; Melting; Phase diagrams; System effectiveness
• ISSN: 2331-8422
• DOI: 10.48550/arxiv.2006.07509

A sufficiently large perpendicular magnetic field quenches the kinetic (Fermi) energy of an interacting two-dimensional (2D) system of fermions, making them susceptible to the formation of a Wigner solid (WS) phase in which the charged carriers organize themselves in a periodic array in order to minimize their Coulomb repulsion energy. In low-disorder 2D electron systems confined to modulation-doped GaAs heterostructures, signatures of a magnetic-field-induced WS appear at low temperatures and very small Landau level filling factors (\(\nu\simeq1/5\)). In dilute GaAs 2D \textit{hole} systems, on the other hand, thanks to the larger hole effective mass and the ensuing Landau level mixing, the WS forms at relatively higher fillings (\(\nu\simeq1/3\)). Here we report our measurements of the fundamental temperature vs. filling phase diagram for the 2D holes' WS-liquid \textit{thermal melting}. Moreover, via changing the 2D hole density, we also probe their Landau level mixing vs. filling WS-liquid \textit{quantum melting} phase diagram. We find our data to be in good agreement with the results of very recent calculations, although intriguing subtleties remain.