Effect of externally applied pressure on the magnetic behavior of Cu2Te2O5(BrxCl1- x)2

The effect of externally applied pressure on the magnetic behavior of Cu2Te2O5(BrxCl1-x)(2) with x=0, 0.73, and 1, is investigated by a combination of magnetic susceptibility, neutron diffraction, and neutron inelastic scattering measurements. The magnetic transition temperatures of the x=0 and 0.73 compositions are observed to increase linearly with increasing pressure at a rate of 0.23(2) and 0.04(1) K/kbar, respectively. However, the bromide shows contrasting behavior with a large suppression of the transition temperature under pressure, at a rate of -0.95(9) K/kbar. In neutron inelastic scattering measurements of Cu2Te2O5Br2 under pressure only a small change to the ambient pressure magnetic excitations were observed. A peak in the density of states was seen to shift from similar to 5 meV in ambient pressure to similar to 6 meV under an applied pressure of 11.3 kbar, which was associated with an increase in the overall magnetic coupling strength.