PRESSURE DEPENDENCE OF CURIE TEMPERATURE OF FERROMAGNETIC LAVES PHASE ALLOYS

The pseudobinary system (Zr1-xNbx)Fe2, with the cubic Laves structure, shows ferromagnetism for samples with x≤0.45. The lattice parameter decreases with increasing Nb content, but the major part of the change in TC is not due to this, as was seen in the case of (Zr1-xTix)Fe2. Zr(Fe1-xCo x)2 behaves similarly. We have studied the effect of high pressure on the Curie temperatures of some of these alloys, using the method of McWhan. All of these samples show a linear decrease of TC with pressure. In the (Zr, Nb)Fe2 series, dT C/dP=-3.3°K/kbar for x=0.3 and -3.5°K/kbar for x=0.35. The permeability decreases with pressure, and the permeability-temperature curves behave as if the compounds become paramagnetic when the Curie temperature falls below 230°K. This is the Curie temperature (at 1 atm) of (Zr 0.6Nb0.4)Fe2, which is the limiting composition of the ferromagnetic region. Zr(Fe1-xCox)2 behaves similarly, with dTC/dP=-4.7°K/kbar for x=0.35 and -6.6°K/kbar for x=0.4. © 1969 The American Institute of Physics.