Strong anisotropy in thin magnetic films deposited on obliquely sputtered Ta underlayers

Abstract

Anisotropy fields in excess of 120 kA/m (1500 Oe) have been produced in 3–5-nm-thick polycrystalline films of Co by oblique sputtering of Ta underlayers. The unusually high anisotropy is magnetostatic in origin and is induced by corrugations on the surface of an obliquely sputtered Ta underlayer. Cross-sectional transmission electron microscopy reveals 4 nm columnar grains of Ta tilted toward the Ta source and elongated perpendicular to the Ta flux in the film plane. The anisotropy field of the Co film increases with both the underlayer thickness and the angle between the Ta source and the film normal. In spin valve samples, the anisotropy is attenuated by more than an order of magnitude across a 4-nm-thick Cu spacer. Magnetoresistance measurements on a spin valve indicate less than 2° dispersion in hard axis directions, and despite the nanometer-scale roughness of the underlayer there is weak broadening of the ferromagnetic resonance line.

Critical angles in DC magnetron glad thin films

“…Among the applications of architected films, one can cite optical sensors [12], nano mechanical [13], pressure sensors [14], and field emitters [15]. Most of the researches concerning GLAD layers were applied to pure material such as Si [7], Cr [4,16], Pt [17], Ta [11,18], W [7], Ti [19] and Co [7]. Others preferred to work on oxides such as TiO 2 [20,21], SiO 2 [21], ZrO 2 [22], or sulfides such as ZnS [23] and Sb 2 S 3 [24].…”

Soft magnetic properties and high frequency characteristics of FeM (M = B, Hf, Zr) and pure Fe films fabricated by oblique deposition

“…The tilted columns broke the structural symmetry with respect to the plane perpendicular to the incident flux direction, instead of that in the plane parallel to the incident deposition plane direction. The tilted crystalline structures of Fe columns induced magnetocrystalline anisotropy while the elongated columns would induce the shape anisotropy [33][34][35].…”

Angular dependence of hysteresis shift in oblique deposited ferromagnetic/antiferromagnetic coupled bilayers

“…This expected behavior is a result of the change in film microstructure as far as a increases. 19,20 In addition, data from both MOKE and FMR show that H u presents a small hump for a around 40 . Fig.…”