Critical evolution of spin-reorientation transition in magnetic CoxNi1-x/Cu(100) films upon precise variation of d-band filling

The ultrathin CoxNi1-x/Cu(100) alloy films with low Co concentration x less than or equal to 10% was prepared for probing the effect of the d-band fil ling on the magnetic behavior. The perpendicular magnetization was observed only for films with x<10%. The spin-reorientation transition from the in-p lane to perpendicular orientation was found to be extremely sensitive to th e Co concentration. The critical thickness for the spin reorientation trans ition was changed drastically from 7.5 to 17.5 Mt, by varying x from 0 to 8 %. Since no significant change in structure and surface morphology was acc ompanied, these findings may be attributed to the critical influence of the d-band filling on the magnetic anisotropy at variation of alloy compositio n.