Forced Magnetostriction, Magnetic Contributions to Bulk Modulus and Thermal Expansion and Pressure Dependence of Curie Temperature in Iron, Cobalt and Nickel

Various magneto-volume effects are calculated in terms of the itinerant electron model. The Lang-Ehrenreich model and Heine's result for the volume dependence of the density of states are used. From the previous numerical results of the magnetic free energy, the temperature variation of its volume derivatives is numerically calculated for Fe, Co and Ni. The magnetic contribution to bulk modulus is estimated as always positive. The magnetic contribution to the thermal expansion coefficient is always negative in Fe, but in Co and Ni it changes its sign, as well as the forced magnetostriction, and becomes positive near the Curie temperature and the pressure dependence of the Curie temperature becomes positive. The spontaneous volume magnetostriction at 0 K is estimated as always positive. It is shown that the present calculated results are consistent with experiment. The Ehrenfest relation is discussed.