In-situ surface stress and magnetic property of CoCrX(X = Pt, Ta)/CrTi bilayer during sputter-deposition

The measurement of the force per width of CoCrX(X = Pt, Ta)/CrTi bilayer showed that both the surface structure state and surface stress of CoCrX magnetic layer can be controlled by regulating the average film stress of CrTi underlayer through a variation of deposition conditions such as deposition rate and temperature as well as underlayer thickness. As the tensile surface stress of CoCrX magnetic layer was more, its coercivity was also more. This was because not a dynamic phase decomposition with a compressive ledge due to high adatoms mobility but an epitaxial film growth with a tensile ledge due to low adatoms mobility. Thus, the development of the crystallographic texture of CoCrX alloy can largely improved its coercivity. It is believed that the principal mechanism determining the coercivity of CoCrX/CrTi film is the optimized development of the crystallographic texture through an evolution of the surface stress of CrTi underlayer.

► Surface stress of CoCrX magnetic layer can be controlled by surface stress of CrTi underlayer.
► Surface stress of CoCrX magnetic layer is closely related to its magnetic property.
► Surface stress of CoCrX magnetic layer is more tensile and its coercivity improves.