Thermal and Quantum Melting Phase Diagrams for a Magnetic-Field-Induced Wigner Solid

In a strongly interacting two-dimensional (2D) electron system, when the Coulomb energy dominates over the kinetic energy, the electrons tend to arrange periodically and form a so-called Wigner solid (WS) ground state. In a GaAs 2D electron system, a magnetic-field-induced quantum WS forms at very low temperature and high magnetic field near filling factor v = 1/5 when the kinetic (Fermi) energy is quenched and the Coulomb energy dominates. In a dilute GaAs 2D hole system, on the other hand, the WS phase forms near v = 1/3 because of the significant Landau level mixing caused by the large hole effective mass. Here we report our measurements [1], using a newly developed technique which probes the melting of the WS via its screening efficiency, of the fundamental temperature vs. filling phase diagram for the 2D holes' WS-liquid thermal melting. Moreover, via changing the 2D holes' density, we also probe their Landau level mixing vs. filling WS-liquid quantum melting phase diagram. We find our data to be in good agreement with the results of very recent calculations [2].

[1] M. K. Ma et al., PRL 125, 036601 (2020).
[2] J. Zhao et al., PRL 121, 116802 (2018).