Collective Charge Excitations below the Metal-to-Insulator Transition in BaVS3

TL;DR

This study investigates the charge dynamics in BaVS3 across its metal-insulator transition, revealing a broad dielectric relaxation linked to orbital ordering and collective charge excitations.

Contribution

It provides new insights into the collective charge excitations and orbital ordering phenomena in BaVS3 below the metal-insulator transition.

Findings

A broad dielectric relaxation mode appears at TMI ~= 67 K.

The dielectric constant reaches ~10^6 near TMI.

Relaxation time is thermally activated, similar to dc resistivity.

Abstract

The charge response in the barium vanadium sulfide (BaVS3) single crystals is characterized by dc resistivity and low frequency dielectric spectroscopy. A broad relaxation mode in MHz range with huge dielectric constant ~= 10^6 emerges at the metal-to-insulator phase transition TMI ~= 67 K, weakens with lowering temperature and eventually levels off below the magnetic transition Tchi ~= 30 K. The mean relaxation time is thermally activated in a manner similar to the dc resistivity. These features are interpreted as signatures of the collective charge excitations characteristic for the orbital ordering that gradually develops below TMI and stabilizes at long-range scale below Tchi.