The origin of low magnetic anisotropy of UFe2: investigation of magnetization and magnetostriction of a U0.8Lu0.2Fe2 single crystal

Magnetization and magnetostriction were investigated on single crystals of UFe2 and U0.80Lu0.20Fe2. The spin reorientation from the <1 1 1> to the <1 0 0> easy-magnetization axis as a consequence of the competition of cubic magnetocrystalline anisotropy constant K10 and magnetoelastic contribution to the magnetic anisotropy ΔK1me was predicted and observed upon the dilution of the uranium sublattice of UFe2 by non-magnetic Lu. Change of the anisotropy type is accompanied by the disappearance of spontaneous magnetostriction distortion (reaching 3x10-3 in UFe2) in U0.8Lu0.2Fe2. Nevertheless, measurements of magnetostriction in magnetic field confirmed that the diluted compound also has very a large magnetostriction constant λ111