Optical manipulation of localized electron transport in disordered chromium nitride

Localization of quasiparticles in disordered and amorphous environments is one of the most intriguing phenomena of condensed matter physics. Thus far, temperature-induced inelastic scattering and magnetic field-induced time-reversal symmetry breaking are the widely known methods to manipulate electron localization in materials. Here, we show conclusive experimental evidence of the photoinduced manipulation of localized electron transport in a prototype-disordered system, chromium nitride (CrN). We inspect this phenomenon by establishing a strong correlation between the temperature-dependent photoconductivity response and the electronic state of CrN. In metallic CrN, the photoresponse is consistently negative, while in semiconducting films, it is positive. However, CrN films exhibiting localized electronic transport at low temperatures exhibit a positive-to-negative photoresponse transition with increasing light intensity. This behavior signifies a localized to metal-like delocalized electronic transition, which we explained through the light-induced breakdown of electron phase coherence responsible for the electron localization and the recharging of traps upon high-intensity photoirradiation mechanisms. Our results illustrate the optical manipulation of electron localization and hold great potential for achieving on-demand localization control for adaptive device applications.