Anisotropic field dependence of the magnetic transition in Cu2Te2O5Br2

TL;DR

This study investigates how the thermal conductivity of Cu2Te2O5Br2 varies with temperature and magnetic field orientation, revealing anisotropic effects on the magnetic transition at 11.4 K.

Contribution

It provides the first detailed measurement of thermal conductivity anisotropy and magnetic field dependence in Cu2Te2O5Br2 near its magnetic transition.

Findings

Thermal conductivity features near T_N=11.4 K are unaffected by magnetic fields parallel to c-axis.

Features become more pronounced with perpendicular magnetic fields.

The magnetic transition temperature increases with magnetic field applied along the a-axis.

Abstract

We present the results of measurements of the thermal conductivity of Cu2Te2O5Br2, a compound where tetrahedra of Cu^{2+} ions carrying S=1/2 spins form chains along the c-axis of the tetragonal crystal structure. The thermal conductivity kappa was measured along both the c- and the a-direction as a function of temperature between 3 and 300 K and in external magnetic fields H up to 69 kOe, oriented both parallel and perpendicular to the c-axis. Distinct features of kappa(T) were observed in the vicinity of T_N=11.4 K in zero magnetic field. These features are unaltered in external fields which are parallel to the c-axis, but are more pronounced when a field is applied perpendicularly to the c-axis. The transition temperature increases upon enhancing the external field, but only if the field is oriented along the a-axis.