Perpendicular anisotropy and magneto-optical Kerr effect of (Ni/Pd) multilayers

Abstract

Nickel film, with total thickness tNi in the range 1000–2000 Å, is known to exhibit perpendicular magnetic anisotropy (PMA), if the film has been deposited at room temperature. This phenomenon is due to the magneto-elastic (ME) effect. The same is also true for the (Ni/Pd)n multilayers, where n is the period (n≥3). In this paper, we have made two kinds of multilayers: one, which does not have a Pd cap layer, belongs to the A-group, and the other, which has, belongs to the B-group. The polar Kerr rotation θk, the polar Kerr ellipticity εk, and the figure of merit (θk)2R, where R is the reflectance, were measured for the two wavelengths, i.e. λ=633 and 442 nm, respectively. The effective PMA energy K⊥ was measured from the vibrating sample magnetometer. It was found that the most favorable multilayer for the magneto-optical (MO) application exists among the A-group samples: i.e. the tNi=1300 Å, tPd=50 Å (seed layer), and n=1 sample. We obtained θk=−9.76 min, εk=−9.13 min, (θk)2R=1.51 (rad)2 at λ=442 nm, and K⊥=3.21×106 erg/cc for this optimal multilayer. Finally, the effects of the Pd seed layer on PMA and MO are also studied.