IS THE MAGNETISM OF HGSE-FE CLEARLY UNDERSTOOD

The high magnetic field magnetization measurements of low composition Hg1-xFexSe (0.0002 < x < 0.003) at temperatures ranging from 1.6 K to 40 K and in magnetic fields up to 20 T are reported. The magnetization in a sample containing only Fe3+ ions (x = 0.0002) is described by th e Brillouin function (j = 5/2). The magnetization in the sample codope d with Ga, containing only Fe2+ is well described in the model of isol ated Fe2+ ions. The latter model takes into account the tetrahedral cr ystal field, the spin-orbit interaction and the Zeeman term. On the ot her hand, the magnetization of sample with both Fe3+ and Fe2+ present simultaneously (x = 0.003) is shown to be different from a simple addi tive superposition of the contributions due to Fe3+ and Fe2+ subsystem s. The possible origin of this discrepancy is discussed.