Study On Preparation And Properties Of Heavy Rare Earth-transition Metal Alloys And Co₂MnSi Alloy Thin Films

In this research,we mainly prepared the heavy rare earth-transition metal(Dy,Tb)FeCo and Heusler alloy Co2MnSi(CMS)thin films.The effects of different process parameters on the magnetic and structural properties of the films were studied as follows:Firstly,DyFeCo thin films with good perpendicular magnetic anisotropy were prepared by direct current magnetron sputtering with a mosaic target of FeCo and Dy.It is found that the influence of sputtering power and gas flow rate on the composition of DyFeCo film is obvious.Two kinds of DyFe Co thin films with rich transition(TM)and rich rare earth(RE)can be prepared by changing the sputtering power.The proper sputtering power and gas flow rate can improve the perpendicular magnetic anisotropy of DyFeCo filmsThe amorphous TbFeCo thin films with good perpendicular magnetic anisotropy were successfully fabricated by radio frequency magnetron sputtering with a mosaic target of FeCo and Tb.By adjusting the sputtering power,the thickness of Ta buffer layer and the magnetic layer,the perpendicular magnetic anisotropy of the TbFeCo thin film was adjusted.Secondly,samples with Si/Ta/MgO/CMS/Ta structure were deposited by DC magnetron sputtering at room temperature.The influence of sputtering power on the in-plane magnetic properties and structural characteristics of CMS films was investigated.Thermomagnetic measurements show that the Ms of the films began to increase when the heating temperature reached 400 ℃.It indicates that the film gradually changed from weak magnetic to strong magnetic.At the same time,as the heating temperature continue to rise,the Ms of the film prepared at higher power increases rapidly,indicating that the more rapidly the magnetic phase transition occurs for a thin film with greater sputtering power.Structural characteristics analysis showed that the film crystallized after annealing at 400 ℃,and the grain size was related to the sputtering power of the film.The change in magnetic properties and sheet resistance after annealing of the film indicates that CMS films with better soft magnetic properties can be obtained with proper sputtering power and annealing temperature.Finally,a kind of multi-layer films were prepared,which is based on Ta as the middle layer,TbFe Co films with different thicknesses as the bottom and top layer respectively.And we successfully observed the continuous flip of two magnetic layers in different external magnetic field.