Principle of Corresponding States of Magnetic Phase Diagram of CuCl2·2H2ZO at Low Temperatures and High Pressures

Abstract

The principle of corresponding states of the magnetic phase diagram of CuCl2·2H2O (TN=4.35K) at low-temperatures, hydrostatic pressures and magnetic fields has been studied by the low-temperature heat capacity measurements. The Néel temperature TN(p) has changed linearly with pressure p(kbar) as TN(p)=TN(0)(1+0.048p) up to 6 kbar at zero external field. The dependence of magnetic interactions on pressure (or inter-ion distance) is revealed to give the larger value of the magnetic Grüneisen constant than expected for the superexchange mechanism. The phase boundary between paramagnetic and antiferromagnetic phases has been examined at high hydrostatic pressures and magnetic fields applied along the spin easy axis. The principle of corresponding states of the magnetic phase diagram of this compound has been checked by a molecular field approximation in the consideration of the pressure dependence of magnetic interactions and anisotropies.