Rattling mode and symmetry lowering resulting from instability of B$_{12}$-molecule in LuB$_{12}$

TL;DR

This paper investigates the rattling modes and symmetry lowering in LuB$_{12}$, attributing large amplitude Lu ion vibrations to a cooperative Jahn-Teller effect that causes lattice distortions and anisotropic charge transport.

Contribution

It provides new insights into the origin of rattling modes and symmetry changes in LuB$_{12}$, linking them to a dynamic Jahn-Teller effect in the boron sublattice.

Findings

Identification of anisotropic charge transport linked to lattice distortions.

Evidence supporting a cooperative Jahn-Teller effect as the cause of rattling modes.

Proposal of a filamentary structure of conductive channels due to lattice distortions.

Abstract

The dodecaboride LuB$_{12}$ with cage-glass state and rattling modes has been studied to clarify the nature of the large amplitude vibrations of Lu ions. Discovered anisotropy of charge transport in conjunction with distortions of the conventional \textit{fcc} symmetry of the crystal lattice may be attributed to coherent motion of Lu ions along singular direction in the lattice. Arguments are presented in favor of cooperative dynamic Jahn-Teller effect in the boron sublattice to be the reason of the rattling mode, lattice distortion and formation of the filamentary structure of the conductive channels.