Origins of substrate-topography-induced magnetic anisotropy in sputtered cobalt-alloy films

Abstract

Cr(001)/CoCrPt (112̄0) films, used in magnetic hard disks, exhibit in-plane magnetic anisotropy when grown over a substrate patterned with shallow grooves. In this experiment, Cr/CoCrPt films are grown over substrates that have been patterned using lithographic techniques to produce well-controlled topography. The in-plane anisotropy, which is of the order of 104 J m−3, increases with the groove height and frequency. This magnetic anisotropy is a result of anisotropic in-plane crystallographic orientation and anisotropic stress. Stress-induced anisotropy accounts for up to 25% of the total in-plane anisotropy, but the major contribution to the anisotropy is a preferential Co c-axis alignment parallel to the groove direction.

Structural order and magnetic anisotropy transition in Co/Fe multilayers

“…The saturation magnetization M s , and the anisotropy field H a , deduced from the magnetization curves, allowed us to determine the anisotropy constant K 1 values ranging from 1.77 to 7.63ϫ10 4 erg/cm 3 . On the origin of such a magnetic texture, a number of experiments have been carried out and several causes have been considered: stresses induced by sample clamping 10 and lattice mismatch, 11 magnetostatic interactions due to stepped substrates, 12,13 magnetostriction phenomena at filmsubstrate interface, 14 mechanical influence, 15 patterning, 16 growing incidence angle, 17,18 structural phase transition in growing layers, 19 and external magnetic field during growth. 6 In previous works, 8,20 an in-plane uniaxial magnetic anisotropy was observed in Co/Fe multilayers grown under the same conditions, and any influence from the substrate material, the stresses induced by sample cutting, and the precipitation of metal oxides was excluded.…”

Growth study of Co thin film on nanorippled Si(100) substrate

“…Self-organized metallic nanoparticles and nanowire arrays have been produced by depositing metal films on patterned substrates. [1][2][3][4][5][6] Such metallic nanostructures have great potential as magnetic materials and for nanophotonic applications, etc. Scratched surfaces prepared by mechanical abrasion with groves separation of the order of 100 nm have been conventionally used for generating texture in Co films in order to achieve desired magnetic anisotropy.…”

Ordered magnetic dipoles: Controlling anisotropy in nanomodulated continuous ferromagnetic films

“…10 Subsequent investigations further reveal properties, like geometrical frustration, domain wall pining, etc., due to dipolar interaction based on spin configurations. 11,12 Several methods, such as ion irradiation through a mask, 6 selective epitaxy, surface modulation, 13 etc., have been studied to control the magnetization configuration in patterned structures. Among them, surface nanomodulation is preferred for its cost effectiveness and simplicity to engineer spin configuration locally.…”