Heterostructured ferromagnet–topological insulator with dual-phase magnetic properties. Issue 14 (19th February 2018)

• Record Type: Journal Article
• Authors: Chang, Shu-Jui; Chuang, Pei-Yu; Chong, Cheong-Wei; Chen, Yu-Jung; Andrew Huang, Jung-Chun; Chen, Po-Wen; Tseng, Yuan-Chieh
• Is Part Of: RSC advances. Volume 8:Issue 14(2018)
• Page Start: 7785
• Page End: 7791
• Publication Date: 2018-02-19
• Subjects: Chemistry -- Periodicals; 540.5
• DOI: 10.1039/c8ra00068a
• Languages: English
• ISSNs: 2046-2069

Abstract

Abstract : In this study we visualized thermodynamically stable chalcogen compounds in the vicinity of a Py/Bi2 Se3 interface with dual magnetic order due to a phase separation effect. Abstract : The introduction of ferromagnetism at the surface of a topological insulator (TI) produces fascinating spin-charge phenomena. It has been assumed that these fascinating effects are associated with a homogeneous ferromagnetic (FM) layer possessing a single type of magnetic phase. However, we obtained phase separation within the FM layer of a Ni80 Fe20 /Bi2 Se3 heterostructure. This phase separation was caused by the diffusion of Ni into Bi2 Se3, forming a ternary magnetic phase of Ni:Bi2 Se3 . The inward diffusion of Ni led to the formation of an FeSe phase outward, transforming the original Ni80 Fe20 /Bi2 Se3 into a sandwich structure comprising FeSe/Ni:Bi2 Se3 /Bi2 Se3 with dual-phase magnetic characteristics similar to that driven by the proximity effect. Such a phenomenon might have been overlooked in previous studies with a strong focus on the proximity effect. X-ray magnetic spectroscopy revealed that FeSe and Ni:Bi2 Se3 possess horizontal and perpendicular magnetic anisotropy, respectively. The overall magnetic order of the heterostructure can be easily tuned by adjusting the thickness of the Bi2 Se3 as it compromises the magnetic orders of the two magnetic phases. This discovery is essential to the quantification of spin-charge phenomena in similar material combinations where the FM layer is composed of multiple elements.