Tailoring Magnetic and Transport Anisotropies in Co100-x-Cu-x Thin Films through Obliquely Grown Nano-Sheets

The magnetic and transport properties of pulsed laser-deposited Co100-x-Cu-x thin films were tailored through their nano-morphology and composition by controlling for the deposition geometry, namely normal or oblique deposition, and their Cu content. All films were composed of an amorphous Co matrix and a textured growth of Cu nanocrystals, whose presence and size d increased as x increased. For x = 50, all films were superparamagnetic, regardless of deposition geometry. The normally deposited films showed no in-plane magnetic anisotropy. On the contrary, controllable in-plane uniaxial magnetic anisotropy in both direction and magnitude was generated in the obliquely deposited films. The magnetic anisotropy field H-k remained constant for x = 0, 5 and 10, H-k approximate to 35 kAm(-1), and decreased to 28 and 26 kAm(-1) for x = 20 and 30, respectively. This anisotropy had a magnetostatic origin due to a tilted nano-sheet morphology. In the normally deposited films, the coercive field H-c increased when x increased, from 200 (x = 0) to 1100 Am-1 (x = 30). In contrast, in obliquely deposited films, H-c decreased from 1500 (x = 0) to 100 Am-1 (x = 30) as x increased. Activation energy spectra corresponding to structural relaxation phenomena in obliquely deposited films were obtained from transport property measurements. They revealed two peaks, which also depended on their nano-morphology and composition.