Micromagnetism And M?ssbauer Spectroscopy Investigation Of Novel Magnetic Materials

Novel magnetic materials have attracted extensive attention in the magnetic society due to the potential applications in the field of electronic devices.For example,magnetic anisotropy is another important factor,in addition to the requirements of high saturation magnetization,to obtain good soft magnetic properties for soft magnetic thin films.In order to further extend the acher limit for traditional soft magnetic films,CoIr soft magnetic films with c-axis orientation has been explored.Because of its large negative magnetocrystalline anisotropy,the distribution of the magnetic moment of these thin films is different from that of the traditional soft magnetic thin films.Compared with CoIr soft magnetic films,NiFe films with stripe domain structure can achieve high frequency response in all directions because of its in-plane rotational anisotropy.In addition,FeNi alloy with L1₀ structure is different from FeNi alloys with general fcc structure,and generally has large coercive force and magnetocrystalline anisotropy constant,which has potential applications in permanent magnet materials.Also because it does not contain expensive rare earth elements,it has been widely investigated.Now,it is the main goal to further understand these new magnetic materials and to improve their magnetic properties.It is of great significance to analyze the magnetic moment distribution of these materials from a microscopic point of view.Therefore,in this paper,the c-axis oriented CoIr soft magnetic films,stripe domain FeNi films and L1₀ FeNi samples prepared by nitridation and denitrification are studied by means of ⁵⁷Fe M???ssbauer spectroscopy together with other macroscopic magnetic characterizations.The main results are as follows:?1?The ⁵⁷Fe probe atoms have been successfully introduced into the films by optimizing the growth process.The structure,macromagnetism and micromagnetism of hcp-CoIr soft magnetic films are studied.Due to the perpendicular anisotropy introduced in the growth process,the deviation of the magnetic moment from the film plane increases slowly with the increase of the film thickness.Nevertheless,the in-plane component of the magnetic moment of the film is still maintaining at high levels with the film thickness reaches micrometer level,that is almost limited in-plane.Combined with XRD and M???ssbauer spectra analysis,the degree of c-axis orientation of the 100 nm film is the worst among all samples.Therefore,optimizing the growth conditions at the initial stage of film growth may further reduce the out of plane component of the magnetic moment with increasing film thickness,and to further improve the soft magnetic properties of the films.?2?Ni₇₅Fe₂₅ thin films with different thicknesses are prepared.The structure,macroscopic and microscopic magnetism of the samples with different thicknesses are studied.When the film thickness exceeds the critical thickness,the stripe-type domain structure appears due to the appearance of the columnar type structure.The perpendicular anisotropy and coercive force increase obviously,and the in-plane rotational anisotropy appears.From our micromagnetism investigation of these films,we show that the stripe type domain structure appears with the increase of the film thickness,resulting in the decrease of the in-plane component of the magnetic moment of these films.?3?Through the study of doping temperature and duration,nitridation and denitrification reaction,semi-ordered phase of FeNi alloy is prepared.The structure,morphology and static magnetism are studied.The conditions of the preparation process and characterization results are analyzed,which can provide reference and ideas for further improving the order degree of the samples.