| Pacific Rim Symposium on Surfaces, Coatings and Interfaces (PacSurf 2014) | |
| Thin Films | Wednesday Sessions |
| Session TF-WeP |
| Session: | Thin Films Poster Session |
| Presenter: | Tsuyoshi Yoshitake, Kyushu University, Japan |
| Authors: | T. Yoshitake, Kyushu University, Japan K. Sakai, Kurume National College of Technology, Japan Y. Asai, Kyushu University, Japan K. Ishibashi, Kyushu University, Japan Y. Noda, Kyushu University, Japan K. Takeda, Fukuoka Institute of Technology |
| Correspondent: | Click to Email |
Since the discovery of GMR and TMR effects, spin-dependent carrier transport has received attention from physical and engineering viewpoints. Whereas GMR and TMR films generally employ nonmagnetic metal and insulator spacers, respectively, we have studied Fe3Si/FeSi2 artificial lattices, in which FeSi2 is semiconducting and its employment as spacers is specific to our research. The combination of Fe3Si and FeSi2 has the following merits: (i) a magnetoresistance effect in the CPP structures is easily detectable since the electrical conductivity of FeSi2 spacer layers is distinctively larger than that of Fe3Si layers; (ii) a spin injection efficiency might be higher than that in TMR films; (iii) the epitaxial growth of Fe3Si layers on Si(111) substrates is successively kept up to the top Fe3Si layer across FeSi2 spacer layers, which is beneficial to the coherent transportation of spin-polarized electrons; (iv) Fe3Si is feasible for a practical use since it has a high Curie temperature of 840 K and a large saturation magnetization, which is half of that of Fe.
A spin valve is one of the most important principle for spin-dependent carrier transport, and the formation of parallel or antiparallel alignments of ferromagnetic layer magnetizations should be realized and controlled in devices with spin valves. Previously, we have prepared Fe3Si/FeSi2 artificial films, wherein interlayer coupling was induced between Fe3Si layers across FeSi2 spacers and the formation of parallel and antiparallel alignments of ferromagnetic layer magnetizations was induced owing to the interlayer coupling [1,2]. The parallel or antiparallel alignments of layer magnetizations can be realized in multilayered films comprising ferromagnetic layers with different coercive forces, and it needs not the precise control of the spacer thickness. In this work, Fe3Si/FeSi2/Fe3Si trilayered films were prepared and the magnetic properties as spin valves were investigated.
An Fe3Si(7000 Å)/FeSi2(7.5 Å)/Fe3Si(1000 Å) artificial film was fabricated by facing-targets direct current sputtering with using a mask method. The magnetization curve was measured using a VSM. The shape of the magnetization curve clearly exhibited the formation of parallel and antiparallel alignments with the magnetic field. This should originate from a difference in the coercive force between the top and bottom FeSi2 layers. The electrical properties accompanied by the change in the magnetization alignment will be presented at the conference.
[1] Ken-ichiro Sakai et al., Jpn. J. Appl. Phys. 51, 028004 (2012).
[2] Ken-ichiro Sakai et al., Jpn. J. Appl. Phys. 53, 02BC15 (2014).