Pressure-induced change of the interlayer exchange interaction from ferromagnetic to antiferromagnetic in CS²CuF⁴ observed by neutron scattering experiments up to 2 GP^a

Abstract

Neutron scattering experiments on the two-dimensional Heisenberg ferromagnets Cs₂ CuF₄ and K₂CuF₄ have been performed around 2 ∼ 3 GPa over 1·4–15 K. At ambient pressure both the intralayer and the interlayer exchange interactions in these two compounds are ferromagnetic. At about 2 GPa, the interlayer exchange coupling in Cs₂ CuF₄ is found to change from ferromagnetic to antiferromagnetic, while the ferromagnetic intralayer exchange interaction is maintained. Contrary to Cs₂CuF₄, the ferromagnetism in K₂Cuf₄ is not destroyed by pressure up to 9 GPa, that was confirmed in the early study of the magnetic susceptibility measurements.

Key Words:

• Cs₂CuF₄
• K₂CuF₄
• Orbital ordering
• Pressure-induced magnetic phase transition
• Neutron scattering