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

A recent study [1] of nonequilibrium dynamics in strongly disordered 2D electron systems (2DES) in Si, with weak coupling to a thermal bath, has provided evidence for MBL-like, prethermal dynamics in the case of a screened or dipolar Coulomb interaction (∝1/r³). In contrast, when the Coulomb interaction is long-range (∝1/r), the dynamics is glassy. Thus, the 2DES in Si is a new, solid-state platform that allows us to explore further how the dynamical signatures of MBL in systems of large sizes compare to those of glasses. Since a key characteristic of glasses is aging, where the response of a system to an external excitation depends on its history, here we employ a waiting-time (t_w) protocol to study the time evolution of conductivity after a temporary change of electron density n_s during t_w. The measurements were performed for different t_w over a wide range of temperatures (T < 1 K) and n_s. The charge dynamics revealed using a waiting-time protocol in the MBL regime is discussed and compared to that in the glassy case [2].

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

[2] J. Jaroszynski et al., Phys. Rev. Lett. 99, 216401 (2007).