[15a-C41-1~6] 10.3 Giant magnetoresistance (GMR), tunnel magnetoresistance (TMR) and magnetic recording technologies

▲ [15a-C41-5] Observation of perpendicular exchange bias in Ir-doped Fe₂O₃/Co thin film system

〇ShuJun YE¹, Satya Prakash Pati¹, Yohei Shiokawa¹, Muftah K.O Al-Mahdawi¹, Tomohiro Nozaki¹, Masashi Sahashi^1,2 (1.Tohoku University, 2.ImPact program)

Keywords:Cr2O3, Fe2O3

The exchange coupling phenomenon at the interface between a ferromagnet (FM) and an antiferromagnet (AFM) has possible applications in spintronic devices. α-Fe₂O₃ (Hematite) is the most stable iron oxide, and it has high Neel temperature (T_N) of 955 K. Thus α-Fe₂O₃/FM system is expected to work at high temperature with high stability. Till now, perpendicular was not observed forα-Fe₂O₃ /FM thin film system; only H_ex for in-plane direction was reported [1]. Because the spin direction ofα-Fe₂O₃ lies parallel to ab-plane above Morin temperature T_M ~ 263 K, it was difficult to observe perpendicular H_ex. On the other hand, in the present spintronic devices, spin direction perpendicular to the film plane is necessary. Our group successfully enhanced T_M of α-Fe₂O₃ thin film to around 400 K by Ir doping [2]. In this work, we fabricated the Ir-doped α-Fe₂O₃ (Ir-Fe₂O₃)/Co exchange coupled thin film and investigated its dependence on Ir-Fe₂O₃ thickness. The sample structures are c-Al₂O₃ substrate/Ir-Fe₂O₃ x/Co 1/Pt 5 (nm). The perpendicular H_ex was observed in this thin film system even for 1-nm-thick Ir-Fe₂O₃ film. Fig. 1 shows temperature dependence of perpendicular H_ex and H_c of c-Al₂O₃ substrate/Ir-Fe₂O₃ 5/Co 1/Pt 5 (nm). Details of thickness dependence will be reported.

This work was partly funded by ImPACT Program of Council for Science, Technology and Innovation (Cabinet Office, Japan Government).

[1] J. Dho et al., Phys. Rev. B, 71 (2005) 180402.
[2] N. Shimomura et al., J. Appl. Phys., 117 (2015) 17C736.