Flexible Co-based Heusler alloy/muscovite heteroepitaxy

Yi-Cheng Chen^1*, Min Yen¹, Anastasios Markou², Benedikt Ernst², Claudia Felser², Ying-Hao Chu¹

¹Department of Materials Science and Engineering, National Chiao Tung University, Hsinchu, Taiwan
²Chemical Physics for Solids, Max Planck Institute, Dresden, Germany

* Presenter:Yi-Cheng Chen, email:ycchen.mse00@g2.nctu.edu.tw

Co-based ferromagnetic Heusler alloys show spin polarization up to 60% with a high Curie temperature of ~700K [1]. This feature provides the spin current which is usually applied to the ferromagnetic electrode in spintronic devices. In this study, we demonstrate the epitaxy of Co₂MnGa Heusler alloy on flexible muscovite substrate, which paves a way toward flexible spintronic devices. The epitaxial Co₂MnGa Heusler/muscovite heterostructure was prepared by magnetron sputtering. We applied three targets (Co, Mn, and MnGa) as the deposition sources to manipulate this composition-sensitive thin film. Muscovite is chosen as the flexible substrate for Heusler alloy since its high melting point meets growth condition for epitaxy. The epitaxy is characterized by X-ray diffraction. The lattice parameter of the film is 5.761A (Bulk: 5.770A) which shows nearly no strain exerted on the film. The in-plane magnetic hysteresis loops measured by SQUID show the saturated magnetization is ~755 emu/cc and coercivity field is ~102 Oe at room temperature. Compare to FePt (1140 emu/cc), the saturated magnetization is relatively low. This relatively small value causes lower energy consumption during the magnetization switch process. To study the origin of the magnetism, we apply XAS-XMCD. The result shows the magnetic moment of Co and Mn are coupled together. After characterizing the physical properties, we apply various bending test to investigate the performance of the film. The bending result shows the magnetization and transport properties of the thin film were modulated. The electrical resistance was measured on a custom bending stage which could vary the bending radius of the sample. The resistance is changed while the bending radius is decreasing, and it goes back to the original state after releasing the sample. The demonstration of Co2MnGa/muscovite heteroepitaxy provides a new perspective on developing the spintronic devices and a huge potential for application of next-generation spintronic devices.

Keywords: Heusler, spintronics, flexible