MAGNETO-OPTICAL INVESTIGATION OF TRIVALENT DYSPROSIUM IN GADOLINIUM TRICHLORIDE

The optical absorption spectrum of 2% Dy3+ in the ferromagnet GdCl3 has been investigated and found to exhibit line shifts and splittings below the Curie temperature (2.2°K), which are attributable to magnetic dipole and exchange interaction between the various states of Dy 3+ and the ordered Gd3+ system. These effects have enabled the exchange field to be measured for a number of different J multiplets, at the lowest temperature obtainable (1.35°K). The exchange field is found to be reasonably constant within a particular multiplet, but the variation between multiplets is more complex than the simple model would indicate. The temperature dependence of the shifts and splittings suggests that the optical effects are a measure of the long-range, rather than the short-range order, although the latter cannot be entirely ruled out.