Thermal quench protocol as a probe of many-body localization and glassiness in strongly disordered 2D electron systems

A strongly disordered two-dimensional electron system (2DES) in Si, with a screened or dipolar Coulomb interaction (∝1/r³) and a weak coupling to a thermal bath, has emerged [1] as a new platform for the study of a prethermal, many-body localization (MBL) regime in systems of large sizes. It has been proposed that thermalization in the MBL regime is characterized by a large hierarchy of timescales for different microscopic configurations to reach local thermal equilibrium, reminiscent of glasses. Here, we employ a thermal quench protocol, in which the total carrier density of a 2DES is kept fixed, to study the fluctuations of conductivity with time. Several different noise statistics are discussed. The observed non-Gaussian noise indicates that the system is not in equilibrium following the quench, but the higher-order statistics are not consistent with the hierarchical picture, in contrast to the dynamics of glasses [2]. This is an important insight into one of the key open questions in the field, namely, how the dynamical signatures of MBL in systems of large sizes compare to those of glassy systems.

[1] L.J. Stanley et al., Nat. Commun. 14, 7004 (2023).

[2] J. Jaroszynski et al., Phys. Rev. Lett. 89, 276401 (2002).