Pressure-induced change of the interlayer exchange interaction from ferromagnetic to antiferromagnetic in Cs2CuF4 observed by neutron scattering experiments up to 2 GPa

Neutron scattering experiments on the two-dimensional Heisenberg ferrogmagn ets Cs-2 CuF4 and K2CuF4 have been performed around 2 similar to 3 GPa over 1.4-15 K. At ambient pressure both the intralayer and the interlayer excha nge interactions in these two compounds are ferromagnetic. At about 2 GPa, the interlayer exchange coupling in Cs-2 CuF4 is found to change from ferro magnetic to antiferromagnetic, while the ferromagnetic intralayer exchange interaction is maintained. Contrary to Cs2CuF4, the ferromagnetism in K2CuF 4 is not destroyed by pressure up to 9 GPa, that was confirmed in the early study of the magnetic susceptibility measurements.