Anisotropic field dependence of the magnetic transition in Cu2Te2O5Br2

摘要

In this paper, we present the results of measurements of the thermal conductivity of Cu2Te2O5Br2, a compound where tetrahedra of Cu2+ ions carrying S = 1/2 spins form chains along the c-axis of the tetragonal crystal structure. The thermal conductivity. 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.( 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.