VARIATION WITH PRESSURE OF MAGNETIC-ORDERING TEMPERATURE OF RARE EARTH SINGLE CRYSTALS

The variation with hydrostatic pressure of the magnetic-ordering temperature of rare earth single crystals has been determined under pressure up to 6 kbar. This effect is determined from the thermal variation of susceptibility in an alternating field. A difference between the variation with pressure of the magnetic ordering temperature of the polycrystal of Gd and that of the single crystal is observed. The variation with pressure of the Curie temperature of polycrystalline Gd is (-1.48±0.02)×10 -3°K bar-1 to be compared to (-1.40±0.02) ×10-3°K bar-1 for the single crystal. The variations with pressure of the Néel temperature of Tb and Dy are, respectively, (-0.84±0.02)×10-3°K bar-1 and (-0.41±0.01)×10-3°K bar-1. An attempt to analyze these variations leads to the conclusion that the exchange energy is dependent upon volume for the major part through the c dependence of exchange interactions between first-neighbors ferromagnetic planes. © 1968 The American Institute of Physics.