2015年 第76回応用物理学会秋季学術講演会

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10 スピントロニクス・マグネティクス » 10 スピントロニクス・マグネティクス(ポスター)

[13p-PA1-1~33] 10 スピントロニクス・マグネティクス(ポスター)

2015年9月13日(日) 13:30 〜 15:30 PA1 (イベントホール)

13:30 〜 15:30

[13p-PA1-23] Positive exchange bias and vertical shift of magnetization curve in Cr2O3/Co exchange coupling system

〇Tomohiro Nozaki1, Satya Prakash Pati1, Yohei Shiokawa1, Muftah K O Al-Mahdawi1, Masashi Sahashi1 (1.Tohoku Univ.)

キーワード:exchange bias,Cr2O3

Magnetoelectric material Cr2O3 has received much attentions as a promising candidate for voltage-controlled spin devices. It is also interesting as a exchange coupling system with unique properties. Before we observed positive-exchange bias (Hex) phenomena for Cr2O3/Pt/Co system. [1] When the cooling filed Hfc during field cool process is sufficient large, spin of Co was pinned against the cooling field direction, i.e. positive-Hex was obtained, while when Hfc is small, normal negative Hex is obtained. Negative coupling between ferromagnet and antiferromagnet surface spin and existence of surface magnetization of antiferromagnet were said to be the requirements to observe positive-Hex. In the previous report, larger Hfc is required to observe positive-Hex for larger Hex sample. For example, Hfc ~ 20kOe (3kOe) was required to observe positive-Hex for samples with Hex ~ 1000Oe (400Oe). In this study we observed positive-Hex for sample with very large Hex (~ 4000Oe) and the Hfc required for positive Hex was as small as 5kOe. In addition, vertical shift of magnetization curve also observed for this sample. We will discuss the possible reason.
[1] T. Nozaki et al., Appl. Phys. Lett., 105 (2014) 212406.