Spin–Orbit-Induced Ising Ferromagnetism at a van der Waals Interface

• Published in: Nano letters 2021-02, Vol.21 (4), p.1807-1814
• Main Authors: Matsuoka, Hideki, Barnes, Stewart Edward, Ieda, Jun’ichi, Maekawa, Sadamichi, Bahramy, Mohammad Saeed, Saika, Bruno Kenichi, Takeda, Yukiharu, Wadati, Hiroki, Wang, Yue, Yoshida, Satoshi, Ishizaka, Kyoko, Iwasa, Yoshihiro, Nakano, Masaki
• Format: Article
• Language: English
• ISSN: 1530-6984; 1530-6992
• DOI: 10.1021/acs.nanolett.0c04851

Magnetocrystalline anisotropy, a key ingredient for establishing long-range order in a magnetic material down to the two-dimensional (2D) limit, is generally associated with spin–orbit interaction (SOI) involving a finite orbital angular momentum. Here we report strong out-of-plane magnetic anisotropy without orbital angular momentum, emerging at the interface between two different van der Waals (vdW) materials, an archetypal metallic vdW material NbSe2 possessing Zeeman-type SOI and an isotropic vdW ferromagnet V5Se8. We found that the Zeeman SOI in NbSe2 induces robust out-of-plane magnetic anisotropy in V5Se8 down to the 2D limit with a more than 2-fold enhancement of the transition temperature. We propose a simple model that takes into account the energy gain in NbSe2 in contact with a ferromagnet, which naturally explains our observations. Our results demonstrate a conceptually new magnetic proximity effect at the vdW interface, expanding the horizons of emergent phenomena achievable in vdW heterostructures.