Building oriented nano-sheets in thin films of Co-MT (MT = V, Cr, Cu, Zn, Cd, Hf) and the generation and enhancement of their magnetic anisotropy

Thin films of Co-rich transition metal or metal Co-MT (MT = V, Cr, Cu, Zn, Cd, Hf) compounds were fabricated as a superposition of oblique nano-sheets (approximate to 300 x 80 x 5 nm for each nano-sheet) from a mixture of Co and MT plasmas. Because the X-ray diffraction patterns of all of the films showed a similar nano-crystalline microstructure, the oblique nano-sheets were visualized by high-resolution transmission electron microscopy. This nano-morphology generated strong in-plane uniaxial magnetic anisotropy, UMA, as we explained in this work, for all the as-deposited films. The evolution of this magnetic anisotropy was studied at temperatures up to 450 degrees C. Three different cases were observed after these heat treatments depending on the MT component of the film: (1) UMA was lost for temperatures approximate to 400 degrees C, (2) UMA retained the same value until the highest temperature was reached, or (3) UMA was enhanced by a factor greater than 2 for the highest temperature. This behavior can be explained by considering of the various processes of structural relaxation and crystallization produced by heat treatment and affected by the nano-sheet morphology. (C) 2016 Elsevier B.V. All rights reserved.