Detailed investigation of the phase transition in K$_{x}$P$_4$W$_{8}$O$_{32}$ and experimental arguments for a charge density wave due to hidden nesting

TL;DR

This study investigates the phase transition in K$_{x}$P$_4$W$_{8}$O$_{32}$, providing experimental evidence for a charge density wave caused by hidden Fermi surface nesting, with insights into the transition's nature and structural effects.

Contribution

It offers detailed experimental analysis of the structural and electronic properties of K$_{x}$P$_4$W$_{8}$O$_{32}$, highlighting the role of hidden nesting and residual strain in the charge density wave transition.

Findings

Charge density wave transition consistent with hidden Fermi surface nesting.

Observation of Fermi surface reconstruction at the Peierls transition.

Evidence of both first and second order transition characteristics.

Abstract

Detailed structural and magnetotransport properties of the monophosphate tungsten bronze K$_{x}$P$_4$W$_{8}$O$_{32}$ single crystals are reported. Both galvanomagnetic and thermal properties are shown to be consistent with a charge density wave electronic transition due to hidden nesting of quasi - 1D portion of the Fermi surface. We also observe the enhancement of electronic anisotropy due to reconstruction of the Fermi surface at the Peierls transition. The resistivity presents a thermal hysteresis suggesting a first order nature characteristics of a strong coupling scenario. However, other measurements such as the change of carriers density demonstrate a second order Peierls scenario with weak coupling features. We suggest that the structural transition driven by the residual strain in the K - P - O environment is responsible for the resistivity hysteresis and modifes the Fermi surface which then helps the rise to the second order Peierls instability.