Omnidirectional Control of Large Electrical Output in a Topological Antiferromagnet

• Published in: Advanced functional materials Vol. 31; no. 15
• Main Authors: Higo, Tomoya, Li, Yufan, Kondou, Kouta, Qu, Danru, Ikhlas, Muhammad, Uesugi, Ryota, Nishio‐Hamane, Daisuke, Chien, C. L., Otani, YoshiChika, Nakatsuji, Satoru
• Format: Journal Article
• Language: English
• Published: Hoboken Wiley Subscription Services, Inc 01.04.2021; Wiley
• Subjects: anomalous hall effect; anomalous nernst effect; antiferromagnetic spintronics; Antiferromagnetism; Chemistry; Demagnetization; Directional control; Ferromagnetism; Heat flux; Magnetic anisotropy; Magnetic devices; Magnetism; Magnetization; Magnets; Materials Science; memory; Memory devices; Physics; Science & Technology - Other Topics; sensors; topological magnet; Topology
• ISSN: 1616-301X; 1616-3028
• DOI: 10.1002/adfm.202008971

Control of magnetization direction is essential for the wide application of ferromagnets; it defines the signal size of memory and sensor. However, the magnetization itself causes a dilemma. While its size matters to obtain strong responses upon its reversal, the large magnetization concomitantly suppresses the range of its directional control because of the demagnetizing field. On the other hand, realization of the desired magnetic anisotropy requires careful engineering of crystalline and interfacial effects to overcome the demagnetization barrier. Thus, it would be ideal if one could find alternative magnets that carry no magnetization but strong responses. The discovery of a topological metallic state in the antiferromagnet Mn3Sn is significant; they host a large Berry curvature in momentum space, enabling the observation of disproportionately large transverse responses such as anomalous Hall and Nernst effects, the key functionalities for replacing ferromagnets in the magnetic devices. Here, the experimental realization of omnidirectional control of the large responses in an antiferromagnet is reported. In particular, it is demonstrated that the absence of shape anisotropy enables the omnidirectional control, and lifts the shape constraint in designing the magnetic devices. This work lays the technological foundation for developing simple‐structured high‐performance devices including multi‐level memory and heat flux sensor. As the topological antiferromagnet Mn3Sn only carries a negligibly small demagnetizing field unlike ferromagnetic materials, the Berry curvature induces large electrical outputs such as anomalous Hall and Nernst effects can be controlled without considering the shape anisotropy, which is a newly demonstrated promising magnetic property for developing simple‐structured high‐performance devices including multi‐level memory and heat‐flux sensor.