Temperature dependence of the magnetostriction and magnetization in single crystal HoFe2

The magnetostriction (λ100) and the magnetic moment of single crystal HoFe2 were measured as a function of temperature down to T=4.2 K. HoFe2 forms a cubic (C15) Laves phase compound with the easy axis of magnetization along the [100] crystallographic direction. At room temperature the magnetostriction is rather small with λ100=−67×10−6 and λ111=200×10−6. λ100 increases substantially with decreasing temperature reaching a value of −745×10−6 at T=4.2 K. This behavior is contrary to that observed in DyFe2 (also [100] easy) where λ111≫λ100. The decrease in λ100 with increasing temperature was found to be much more rapid than could be explained by lowest order single-ion magnetoelastic theory. On the other hand, magnetostriction measurements of λ111 over the temperature range 275–325 K result in a temperature dependence which can satisfactorily be explained by the single-ion model. The spontaneous magnetic moment at T=0 K is 134.5 emu/g. Taking the the gJ value of 10 μb for the Ho3+ sublattice moment results in an Fe moment of 1.67 μb. This value is nearly equal to those previously obtained in other RFe2 compounds. The magnetization curves at room temperature along the principal crystallographic directions yield anisotropy constants K1=5.5×106 erg/cm3 and K2=6.4×106 erg/cm3.