Evidence of a strong perpendicular magnetic anisotropy in Au/Co/MgO/GaN heterostructures

Xue Gao (1, 2) , Baishun Yang , Xavier Devaux (1) , Hongxin Yang (3) , Jianping Liu (2) , Shiheng Liang (1) , Mathieu Stoffel (1) , Ludovic Pasquier (1) , Bérangère Hyot (4) , Adeline Grenier (4) , Nicolas Bernier (4) , Sylvie Migot (1) , Stéphane Mangin (1) , Hervé Rinnert (1) , Chunping Jiang (2) , Zhongming Zeng (2) , Ning Tang (5) , Qian Sun (2) , Sunan Ding (2) , Hui Yang (2) , Yuan Lu (1)

1 IJL - Institut Jean Lamour
2 Key Laboratory of Nanodevices and Applications, Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences, Suzhou 215123, China
3 Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences
4 CEA-LETI - Commissariat à l'énergie atomique et aux énergies alternatives - Laboratoire d'Electronique et de Technologie de l'Information
5 Peking University [Beijing]

We report a strong perpendicular magnetic anisotropy (PMA) in Au/Co/MgO/GaN heterostructures from both experiments and first-principles calculations. The Au/Co/MgO heterostructures have been grown by molecular beam epitaxy (MBE) on GaN/sapphire substrates. By carefully optimizing the growth conditions, we obtained a fully epitaxial structure with a crystalline orientation relationship Au(111)[ 110]// Co(0001)[11 20]//MgO(111)[10 1]//GaN(0002)[11 20]. More interestingly, we demonstrate that a 4.6 nm thick Co film grown on MgO/GaN still exhibits a large perpendicular magnetic anisotropy. First-principles calculations performed on the Co (4ML)/MgO(111) structure showed that the MgO(111) surface can strongly enhance the magnetic anisotropy energy by 40% compared to a reference 4ML thick Co hcp film. Our layer-resolved and orbital-hybridization resolved anisotropy analyses helped to clarify that the origin of the PMA enhancement is due to the interfacial hybridization of O 2p and Co 3d orbitals at the Co/MgO interface. The perpendicularly magnetized Au/Co/MgO/GaN heterostructures are promising for efficient spin injection and detection in GaN based opto-electronics without any external magnetic field.

Domaines: Science des matériaux [cond-mat.mtrl-sci]

Xue Gao, Baishun Yang, Xavier Devaux, Hongxin Yang, Jianping Liu, et al.. Evidence of a strong perpendicular magnetic anisotropy in Au/Co/MgO/GaN heterostructures. Nanoscale Advances, 2019, 1 (11), pp.4466-4475. ⟨10.1039/c9na00340a⟩. ⟨hal-02999610⟩