| Magnetic domains and domain walls are major features in magnetism. The microstructure of a magnetic domain and the domain wall type are important factors that affect material′s properties and determine material′s applications. For instance, soft magnetic thin films exhibit a wide range of applications, such as perpendicular magnetic recording, magnetic sensors, high-frequency inductor devices, miniature sensor, noise suppressor, and spin valve devices. The domain structure and domain walls play important roles in their applications. In perpendicular magnetic recording, there is none out-of-plane stray field in a soft magnetic underlayer. In high-frequency applications, there is none stripe domains with large film thickness to get well high-frequency properties. However, traditional single layer Fe-, FeCo- based soft magnetic films can’t satisfy these conditions well. To accomplish these initiatives, researchers have done many works in this field. Néel wall can be formed in thicker soft magnetic films through several promising method, such as construction of multilayer structure films by inserting nonmagnetic insulating phase or introduction of antiferromagnetic coupling. However, the construction of multilayer structure film is somewhat cumbersome and complex, and the magnetism of the film is nonuniform. If we accomplish thus problem in a single magnetic layer, we can achieve the optimation of film preparation process and the magnetism uniform of film. Therefore, it would be more innovative and convenient if the Néel wall in a thicker layer can be achieved by changing the intrinsic parameters of the magnetic material. The c-oriented hcp-CoIr film is a viable material.In this work, we have prepared the c-axis oriented hcp-CoIr soft magnetic films with negative magnetocrystalline anisotropy through magnetron sputtering, and investigated the pressure, thickness, thickness, etc. dependence of the c-axis oriented hcp-CoIr soft magnetic films, and the thickness, component dependence of the microscopic magnetic domain stricture. The main results are listed as follows:(1) The c-axis orientation of hcp-Co Ir films is largely denpendent on the sputtering conditions of seed-layer; In order to fabricate high c-axis oriented hcp-CoIr soft magnetic films, it’s necessary to get the fcc-Au seed-layer with good [111] orientation.(2) The Lorenz-TEM and MFM image shows that the domain wall of the high oriented hcp-Co83Ir17 soft magnetic film is Néer wall with the thickness of 55 nm. The formation and evolution of the domain wall of the Co83Ir17 film by Lorenz TEM match well with the in-plane hysteresis loop both in easy axis and hard axis.(3) Theoretical calculations show that the introduction of negative magnetic anisotropy in the c-axis direction can significantly improve the total energy density of Bloch wall without changing the total energy density of Néer wall for the film, which inevitably results in the increasing of the critical thickness of Néer wall. In this work, we have observed the critical transition thickness from Néel wall to Bloch wall of c-axis oriented Co81Ir19 soft magnetic film through experimental observations and theoretical calculations about 130 nm.(4) The c-axis oriented uniform hcp-CoIr films with different component are fabricated by the synchronous movement of Ir piece. The MFM images show that the microscope domain structure of the oriented hcp-CoIr films changes from maze domain, stripe domain, Bloch wall to Néer wall with the increasing of Ir. This indicates that we could control the microscopic magnetic domain structure and domain wall form of the film by the change of the component of the Ir. |
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