Observation of an exotic insulator to insulator transition upon electron doping the Mott insulator CeMnAsO.

Wildman, E J; Lawrence, G B; Walsh, A; Morita, K; Simpson, S; Ritter, C; Stenning, G B G; Arevalo-Lopez, A M et al. · Nat Commun · 2023

basic_science · Level V

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Abstract

A promising route to discover exotic electronic states in correlated electron systems is to vary the hole or electron doping away from a Mott insulating state. Important examples include quantum criticality and high-temperature superconductivity in cuprates. Here, we report the surprising discovery of a quantum insulating state upon electron doping the Mott insulator CeMnAsO, which emerges below a distinct critical transition temperature, T<sub>II</sub>. The insulator-insulator transition is accompanied by a significant reduction in electron mobility as well as a colossal Seebeck effect and slow dynamics due to decoupling of the electrons from the lattice phonons. The origin of the transition is tentatively interpreted in terms of many-body localization, which has not been observed previously in a solid-state material.