Structural Phase Transition in a Two-Dimensional Antiferromagnet Induced by Static Magnetic Field under High Pressure at Liquid Helium Temperature

Abstract

After complete removal of the pressure on (C₂H₅NH₃)₂CuCl₄, an interchange within in-plane spin axes is recognized by magnetic measurements and that of crystalline axes by X-ray analysis. The condition indispensable for this phenomenon is the application of external magnetic field (2∼3 kOe) along its second easy axis under hydrostatic pressure (∼7 kbar) at liquid helium temperature. A successive process along the newly built second easy axis results in a recovery to the initial state of spin axes.