Low-temperature dielectric anomaly arising from electronic phase separation at the Mott insulator-metal transition

Abstract Coulomb repulsion among conduction electrons in solids hinders their motion and leads to a rise resistivity. A regime of electronic phase separation is expected at the first-order transition between correlated metal paramagnetic Mott insulator, but remains unexplored experimentally as well theoretically nearby T = 0. We approach this issue by assessing complex permittivity via dielectric spectroscopy, which provides vivid mapping deep insight into its microscopic nature. Our experiments utilizing both physical pressure chemical substitution consistently reveal strong enhancement quasi-static constant ε 1 when correlations are tuned through critical value. All experimental trends captured dynamical mean-field theory single-band Hubbard model supplemented percolation theory. findings suggest similar ’dielectric catastrophe’ many other materials explain previous observations that were assigned multiferroicity or ferroelectricity.