Evidence of electronic phase separation in the strongly correlated semiconductor YbB12

TL;DR

This study provides evidence that YbB12, a strongly correlated semiconductor, exhibits electronic phase separation with dynamic charge stripes, revealing a heterogeneous electronic structure that influences its exotic dielectric state.

Contribution

First demonstration of electronic phase separation and dynamic charge stripes in YbB12, advancing understanding of its complex electronic heterogeneity.

Findings

YbB12 is a heterogeneous compound with phase-separated electronic regions.

Charge stripe configurations change with temperature, indicating a crossover in electronic patterns.

Discovery of stripes helps explain the nature of the dielectric state in Kondo insulators.

Abstract

The studies of high-quality single-domain crystals of YbB12 were carried out by the precise x-ray diffraction technique in combination with the low temperature polarized THz - infrared spectroscopy and accurate magnetotransport measurements. It has been shown for the first time that this archetypal strongly correlated system with a metal-insulator transition to a mysterious dielectric ground state with a metal Fermi surface (Science 362, 65-69 (2018) and ibid 362, 32-33 (2018)) is actually a heterogeneous compound in the regime of electronic phase separation. Changes in the configuration of the discovered dynamic charge stripes are investigated upon cooling, as a result, a conclusion is drawn in favor of a crossover between different patterns of the filamentary electronic structure penetrating the semiconducting matrix of YbB12. We argue that the discovery of stripes in YbB12 is fundamental, elucidating the nature of exotic dielectric state in Kondo insulators.