Structural, Magnetic, and Electric Properties of Pt/Co/Au/Cr2O3/Pt Thin Film with Cr2O3 Layer below 25 nm

• Published in: Journal of the Magnetics Society of Japan 2021/07/01, Vol.45(4), pp.101-105
• Main Authors: Shiratsuchi, Y., Shen, J., Tao, Y., Takahara, K., Toyoki, K., Nakatani, R.
• Format: Article
• Language: English
• Subjects: Anisotropy; antiferromagnet; Bias; Chromium oxides; Cobalt; Coercivity; Cr2O3; Crystallization; Electric fields; Electric properties; Exchanging; Flux density; Gold; insulator; Magnetic anisotropy; Magnetic properties; Magnetron sputtering; perpendicular magnetic anisotropy; Platinum; Thick films; Thickness; thin film; Thin films
• ISSN: 1882-2924; 1882-2932
• DOI: 10.3379/msjmag.2107R004

  Perpendicular exchange bias using magnetoelectric Cr2O3 has an electric-field triggered switching ability, and the thickness limit of the Cr2O3 layer for inducing this bias is a topic of research. In this paper, we investigated the structural, magnetic, and electric properties of Pt/Co/Au/Cr2O3/Pt thin films with a Cr2O3 layer in the thickness range of 5.7 to 25 nm. By using a magnetron sputtering method, a well-crystallized Cr2O3(0001) layer was formed in 5.7-nm-thick Cr2O3. All studied films showed perpendicular magnetic anisotropy. The uniaxial magnetic anisotropy energy density increased as the Cr2O3 thickness decreased, and 810±90 kJ/m3 was obtained for the film with 5.7-nm-thick Cr2O3. Perpendicular exchange bias was evaluated above 80 K, and an exchange anisotropy energy density of 0.30 mJ/m2 was observed for the film with a 25-nm-thick Cr2O3 at 80 K. The exchange bias could not be observed below 18 nm. Instead, coercivity enhancement, which yields the exchange bias by precisely controlling interfacial exchange coupling, was observed. The electric resistivity was about 5 × 105 Ωm for the 5.7-nm-thick Cr2O3 layer, which is sufficiently high for magnetoelectric applications.