Observation of dynamic charge stripes in Tm0.19Yb0.81B12 at the metal-insulator transition

TL;DR

This study combines low-temperature charge transport and X-ray diffraction to reveal dynamic charge stripes in Tm0.19Yb0.81B12, linked to Jahn-Teller effects and ion rattling, during the metal-insulator transition.

Contribution

It provides the first evidence of dynamic charge stripes in Tm0.19Yb0.81B12, highlighting the role of ion rattling and Jahn-Teller effects in charge dynamics.

Findings

Detection of symmetry lowering in Tm0.19Yb0.81B12 crystals.

Observation of dynamic charge stripes within the semiconducting matrix.

Estimation of charge carrier quantum motion frequency (~2.4×10^11 Hz).

Abstract

Higher accuracy low temperature charge transport measurements in combination with precise X-ray diffraction experiment have allowed detecting the symmetry lowering in the single domain Tm0.19Yb0.81B12 crystals of the family of dodecaborides with metal-insulator transition. Basing on the fine structure analysis we discover formation of dynamic charge stripes within the semiconducting matrix of Tm0.19Yb0.81B12. The charge dynamics in these metallic nano-size conducting channels is characterized by broad-band optical spectroscopy that allowed estimating the frequency (~2.4 10^11 Hz) of quantum motion of the charge carriers. It is suggested that caused by cooperative Jahn-Teller effect in the boron sub-lattice, the large amplitude rattling modes of the Tm and Yb ions are responsible for modulation of the conduction band along [110] direction through the variation of 5d-2p hybridization of electron states.