Unconventional Charge-density-wave Order in a Dilute d-band Semiconductor

TL;DR

This paper reports the discovery of charge density wave order in a dilute d-band semiconductor, BaTiS3, revealing strong electron-phonon coupling and an unusual transition with increased carrier mobility, expanding understanding of CDW in semiconductors.

Contribution

It demonstrates the existence of CDW order in a low carrier concentration semiconductor, a phenomenon previously uncommon in such systems.

Findings

CDW order found in BaTiS3 via multiple experimental techniques

Unusual transition with increased carrier mobility observed

BaTiS3 serves as a platform for studying CDW physics in dilute systems

Abstract

Electron-lattice coupling effects in low dimensional materials give rise to charge density wave (CDW) order and phase transitions. These phenomena are critical ingredients for superconductivity and predominantly occur in metallic model systems such as doped cuprates, transition metal dichalcogenides, and more recently, in Kagome lattice materials. However, CDW in semiconducting systems, specifically at the limit of low carrier concentration region, is uncommon. Here, we combine electrical transport, synchrotron X-ray diffraction and optical spectroscopy to discover CDW order in a quasi-one-dimensional (1D), dilute d-band semiconductor, BaTiS3, which suggests the existence of strong electron-phonon coupling. The CDW state further undergoes an unusual transition featuring a sharp increase in carrier mobility. Our work establishes BaTiS3 as a unique platform to study the CDW physics in the dilute filling limit to explore novel electronic phases.