The Magnetic Anisotropy of Copper Sulphate Pentahydrate, CuSO4·5H2

In Part I of this paper were reported some magnetic measurements on the crystal of CuS${\mathrm{O}}_{4}$\ifmmode\cdot\else\textperiodcentered\fi{}5${\mathrm{H}}_{2}$O. The crystal, though triclinic, has nearly uniaxial magnetic symmetry, and the symmetry axis is the direction of minimum susceptibility for the crystal. This observed uniaxial symmetry and the negative sign of the anisotropy were shown to follow naturally from the known fine structure of the crystal, and the direction of the symmetry axis also is nearly that predicted from the structure. In the present paper are described further magnetic studies on the crystal, and a more detailed correlation with its structure. The magnetic data are also discussed in relation to the magnitude and the asymmetry of the internal electric fields acting on the ${\mathrm{Cu}}^{++}$ ions in the crystal. A general method is described for determining, for any triclinic crystal, the principal magnetic axes and susceptibilities, i.e., the constants of the magnetic ellipsoid.