Magnetic and crystal structure of copper(II) fluoride

A powder sample of the monoclinic, weak ferromagnet CuF2 was investigated by neutron diffraction. Using the profile method, the crystal structure was refined and the spin configuration determined. The layer type structure with planar quadratic fluorine coordination of Cu2+ (3d9) and the magnetic structure are remarkably similar to those of AgF2. The spin configuration is however different from the magnetic structures of other 3d-fluorides; the magnetic unit cell is doubled with respect to the chemical cell (am = 2a, P21/c). The ordered magnetic saturation moment corresponds to quenched orbital momentum.