Regensburg 2019 – scientific programme

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MA: Fachverband Magnetismus

MA 32: Magnetic recording, sensors and other devices

MA 32.4: Talk

Wednesday, April 3, 2019, 12:45–13:00, H53

Improvement of band matching by monolayer Ni insertion at the Co₂FeGa_0.5Ge_0.5/Ag interfaces in current-perpendicular-to-plane pseudo spin valves — •Björn Büker^1,2, Jin Won Jung², Yuya Sakuraba², Yoshio Miura², Taisuke Sasaki², Andreas Hütten¹, and Kazuhiro Hono² — ¹Bielefeld University, Bielefeld, Germany — ²NIMS, Tsukuba, Japan

All-metallic current-perpendicular-to-plane giant magnetoresistive devices (CPP-GMR) using half-metallic Heusler alloys have gathered a lot of interest lately, e.g. as next generation read heads for high density hard drives. For further enhancement of the MR ratio, interfacial spin-dependent scattering, which is directly related to the electronic band matching of the Heusler and the non-magnetic spacer, is an important factor for optimization. Recently Jung et al. have demonstrated a large enhancement of the MR ratio to more than 80% in Co₂FeGa_0.5Ge_0.5 /Ag/ Co₂FeGa_0.5Ge_0.5 (CFGG) structures by inserting thin layers of NiAl at the CFGG/Ag interface, even though Al showed undesired interdiffusion. Therefore, we have performed a systematic study on thin layers of pure Ni at the CFGG/Ag interface, in order to investigate the mechanism of the enhanced magnetoresistance caused by the inserted layer.
The pseudo spin valve (PSV) films were prepared on a MgO(001) substrate. The MR ratio increased significantly from 27% for t_Ni=0 nm to 44% for t_Ni=0.21 nm. HRTEM images of the interface along with atomic resolution EDS elemental mappings confirm a Ni monolayer at the interface.