Thermal conductivity of the diamond-chain compound Cu_3(CO_3)_2(OH)_2

TL;DR

This study investigates the low-temperature thermal conductivity of the diamond-chain compound Cu_3(CO_3)_2(OH)_2, revealing phonon-dominated heat transport strongly influenced by magnetic excitations and field-induced changes.

Contribution

It provides the first detailed analysis of phononic thermal conductivity in this compound, highlighting the role of magnetic excitations in phonon scattering.

Findings

Thermal conductivity shows a three-peak structure at low temperatures.

Magnetic fields significantly alter thermal conductivity in correlation with magnetic specific heat.

Magnetic excitations mainly scatter phonons, not transport heat.

Abstract

Thermal conductivity (\kappa) of a distorted spin diamond-chain system, Cu_3(CO_3)_2(OH)_2, is studied at low temperatures down to 0.3 K and in magnetic fields up to 14 T. In zero field, the \kappa(T) curve with heat current along the chain direction has very small magnitudes and shows a pronounced three-peak structure. The magnetic fields along and perpendicular to the chains change the \kappa strongly in a way having good correspondence to the changes of magnetic specific heat in fields. The data analysis based on the Debye model for phononic thermal conductivity indicates that the heat transport is due to phonons and the three-peak structure is caused by two resonant scattering processes by the magnetic excitations. In particular, the spin excitations of the chain subsystem are strongly scattering phonons rather than transporting heat.