MIT News August 19, 2021
Experimental realization of many-body localization (MBL) in solid-state systems has remained challenging. A team of researchers in the US (MIT, Argonne National Laboratory, Brookhaven National Laboratory, University of Wisconsin, Oak Ridge National Laboratory, UC Santa Barbara, University of Pennsylvania) reports evidence of a possible phonon MBL phase in disordered GaAs/AlAs superlattices. Through grazing-incidence inelastic X-ray scattering, they observed a strong deviation of the phonon population from equilibrium in samples doped with ErAs nanodots at low temperature, signaling a departure from thermalization. This behavior occurs within finite phonon energy and wavevector windows, suggesting a localization-thermalization crossover. They support their observation by proposing a theoretical model for the effective phonon Hamiltonian in disordered superlattices and showing that it can be mapped exactly to a disordered 1D Bose–Hubbard model with a known MBL phase. The work provides momentum-resolved experimental evidence of phonon localization, extending the scope of MBL to disordered solid-state systems…read more. TECHNICAL ARTICLE
The setup for the milli-electronvolt inelastic X-ray scattering that probes the many-body localization in the disordered superlattice system. Credit: Researchers