Phenomenological approach of the thermodynamic properties of CDW (SDW) systems

TL;DR

This paper explores the thermodynamic properties of charge density wave (CDW) and spin density wave (SDW) systems using a phenomenological approach, highlighting classical mean field behavior across various materials.

Contribution

It extends the understanding of thermodynamic properties in CDW/SDW systems, connecting experimental observations with a phenomenological framework.

Findings

Specific heat jump increases with transition temperature

Elastic stiffness decreases at phase transition

Thermodynamic behavior follows classical mean field BCS type

Abstract

The microscopic description of the CDW phase transition is still debated and remains controversial. The question is how to extend the Peierls picture to real systems in higher dimensions. A general tendency is found in the thermodynamic properties such as the specific heat jump DCp and the decrease of the longitudinal elastic stiffness constant DC11/C11 at the CDW phase transition in several materials, such as quasi-one dimensional (K0.3MoO3), transition metal dichalcogenide compounds (2H-NbSe2), rare earth tritellurides (TbTe3, ErTe3, HoTe3) and intermetallic compound (Lu5Ir4Si10). DCp and DC11/C11 increase as the temperature of the phase transition TCDW and TCDW2 respectively. The same tendency is found at the spin density phase transition in chromium and CuGeO3.Thermodynamic properties of almost all CDW systems, although it has been recognized to exhibit large fluctuations, follow the classical mean field BCS type behavior.