Pressure-Induced Transition of the Interlayer Exchange Interaction from Ferromagnetic to Antiferromagnetic Observed in the Two-Dimensional Ferromagnet (CH3NH3)2CuCl4through Magnetic Susceptibility and Neutron Scattering Measurements

At ambient pressure, both the intralayer and the interlayer exchange interactions in the layered compound (CH 3 NH 3 ) 2 CuCl 4 are ferromagnetic. Magnetic susceptibility and neutron scattering experiments performed under pressures up to about 1 GPa revealed that the interlayer exchange interaction turns into an antiferromagnetic one at a pressure between 0.41 GPa and 0.61 GPa, while the intralayer exchange interaction remains ferromagnetic. The spin structure in the antiferromagnetic phase is still collinear at least up to 1.1 GPa.