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Research of Cu,Cr Co-doped on Properties and Magnetic Exchange Bias Effect of Sm₂-Co₁₇/Cu Films

Author: WangZuo
Tutor: FangQingQing
School: Anhui University
Course: Materials Science
Keywords: SmCo films structure magnetic exchange bias effect
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Type: Master's thesis
Year: 2014
Downloads: 1
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Abstract

SmCo as a new rare earth permanent magnet material, has been widespread concern. Its application in the electro-acoustic telecommunications devices, electricals, electronics and other industries are more widely. SmCo permanent magnetic materials have good magnetic properties, low temperature coefficient and great uniaxial magnetic anisotropy, which make it be a great potential for development of rare earth permanent magnet materials.In this paper, SmCoCu/Cu/Cr and SmCoCuCr/Cu/Cr films based on Si(100) substrates and glass substrates were prepared by pulsed laser deposition(PLD) method. We focus on the magnetic layer and the non-magnetic layer regulation on the structure, morphology and magnetic properties of Sm2Co17films, the main contents are as follows:1. The effects of SmCo magnetic layer thickness and processing plated Cu seed layer on the structure and magnetic of Sm2Co17/Cu/Cr films have been systematic studied. It was found that increasing the SmCo magnetic thickness was conducive to increase coercivity, the right amount of the magnetic layer thickness can increase the coercivity. Meanwhile, maintained the same Co content, by changing the content of Sm, adjusted SmCo composition ratio, it was found the right amount of Sm was conducive to grow Sm2Co17. It was also found, right amount of Cu seed layer thickness helped Cu (111) grow and promoted the growth of Sm2Co17. Quality of Cu (111) crystal layer was conducive to the,growth of Sm2Co17.2. By adjusting the content of non-magnetic elements Cu and Cr, the structure and magnetic properties of Sm2Co17films were systematic studied. It was found that the incorporation of a small amount of Cu in the original SmCo ingredients help to improve the coercivity of magnetic thin films. Also found that adding a small amount of Cr help to promote the film grain refinement to improve the coercivity. Meanwhile, it was found that the crystalline quality of the films was enhanced by decreasing the surface roughness of films. 3. The magnetic exchange bias effect of Sm2Co17has been systematic studied. We found that there is a clear magnetic exchange bias phenomenon in Sm2Co17(Cu,Cr)/Cu/Cr film. The experiments found that the exchange bias field is increased with increasing Cr content and a small amount of Cu can improve the exchange bias effect. However, the increase of the Sm content does not significantly improve the strength of exchange bias field. Therefore, the effect of exchange bias can be improved by adjusting the non-magnetic element for Sm2Co17structure.4. The mechanism of the exchange bias phenomenon of Sm2Co17films was deeply studied. We suggested that there is a ferromagnetic phase (SmCo) and a nonferromagnetic phase (Cu,Cr), magnetic phase in films, and resulted in the exchange coupling of the ferromagnetic phase and the non-magnetic phase on the interface of layer films. In the films prepared, the SmCo magnetic layer and the (Cu, Cr) non-magnetic layer are overlaped each other. It was found that the pinning effect in films is formed with the increasing of Cr layer. The stronger pinning effect makes nonferromagnetic action of SmCo films stronger and positive exchange bias field increased; few incorporation Cu content can affect the pinning effect, but hs little effect on the exchange bias; In addition, when the thickness of the non-ferromagnetic layer remains unchanged, the decrease of exchange bias field due to the increase of SmCo magnetic layer thickness, which consistes with the theoretical results. When ferromagnetic(FM) layer is less than the size of domain wall, and the nonferromagnetic layer thickness remains unchanged, the theoretical studies showed that the exchange bias field is inversely proportional to the thickness of the FM layer, namely, HE∝1/tFM, If increased content of Sm element in the magnetic layer, the competitive effect of the ferromagnetic layer strong, so that causes positive bias of exchange bias become smaller, and results in the decrease of bias field.

Research of Cu,Cr Co-doped on Properties and Magnetic Exchange Bias Effect of Sm2-Co17/Cu Films

Abstract

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Research of Cu,Cr Co-doped on Properties and Magnetic Exchange Bias Effect of Sm₂-Co₁₇/Cu Films