Alloying and strain relaxation effects on spin-reorientation transitions inCoxNi1−x∕Cu3Au

Abstract

The crystalline structure and the magnetic properties of Co x Ni 1−x /Cu 3 Au͑100͒ films were characterized as functions of thickness and alloy composition. No apparent alloy effect on the crystalline structure was observed with x up to 11%. As the film thickness increases above ϳ8 monolayers ͑ML͒, the films clearly exhibited a progressively more relaxed structure. Due to the strain relaxation, both the first and the second spinreorientation transitions ͑SRT͒ occurred within 20 ML. The thickness region with perpendicular magnetization was strongly reduced by increasing the Co concentration. For x Ͼ 10%, no SRT was observed. By combining both the alloy effect and the strain relaxation effect, the SRT boundaries in the phase diagram can be described in a phenomenological model on the basis of magnetoelastics.

Canted magnetization in Fe thin films on highly oriented pyrolytic graphite

“…The density of magnetic anisotropy can be described as E ¼ K eff Ásin 2 h, where K eff is the effective anisotropy energy and h is the angle between the direction of magnetization and the surface normal. 24 Positive K eff defines the perpendicular easy direction, whereas negative K eff defines the in-plane easy direction. K eff is composed of the surface/interface anisotropy and volume contributed shape and crystalline anisotropy.…”

“…25 Therefore, the stable canted magnetization in Fe/s-HOPG films suggests a volume-contributed perpendicular anisotropy that is sufficiently large to compensate for the in-plane shape anisotropy. 24 The sputtering-induced broken carbon bonds on the HOPG surface may bond more strongly to the Fe atoms and lead to strain-induced magnetoelastic anisotropy, which causes canted magnetization.…”

“…M s is the magnetic moment density of Fe (2.5 l B /atom). 12,24 The bulk magnetocrystalline anisotropy of bcc Fe K Cry. ¼ 0.047 MJ/m 3 , preferring the [100] directions, is relatively small and unable to overcome the large in-plane shape anisotropy.…”

Hydrogen adsorption promoted perpendicular magnetic anisotropy in nano-structured Fe coverage on Pd/W{112} faceting surface

“…18 From the condition of minimum energy E a , the magnetization prefers the perpendicular (in-plane) direction if K eff > 0 (<0). Thus, spin reorientation transition (SRT) happens when K eff changes signs and we can get the SRT critical thickness d c by solving K eff ¼ 0.…”

“…3 and Fe magnetization M ¼ 2:4 l B =atom, we can deduce the surface anisotropy K s ¼ 0.96 and 1.34 meV/atom for Fe coverage on Pd/W{112} before and after hydrogen exposure, respectively. 16,18,22 The hydrogen exposure enhances the perpendicular surface anisotropy by 40%. However, it is hard to tell whether the enhancement originates from Fe surface or Fe/Pd interface.…”