Large magneto-optical Kerr effect and real-time imaging of magnetic domain in an antiferromagnet

Published: January 26, 2018


Daniel B. Gopman, Robert D. Shull, Yury Kabanov, Huiyan Man, L. Wu, O.M.J. van 't Erve, D. Rees, Yufan Li, S. Pantakar, C L. Chien, J Orenstein, Tomoya Higo, Satoru Nakatsuji


When a linearly polarized light beam is incident upon the surface of a magnetic material, the reflected light becomes elliptically polarized and the ellipse major axes undergo a polar rotation within the polarization plane of the incident light: this magneto-optical Kerr effect (MOKE) been intensively studied in a variety of ferro- and ferrimagnetic materials owing to its value for examining magnetization and magnetization reversal behavior as well as magnetic domain observations. MOKE also generates significant interest for candidate technological applications including magneto-optical recording technology as well as for the optimization of candidate magnetic devices. Recently, there has been a surge of interest in antiferromagnets as prospective spintronic materials for high density and ultrafast memory devices, owing to their low sensitivity to external magnetic fields and orders of magnitude faster spin dynamics compared to their ferromagnetic counterparts. However, sensing the antiferromagnetic Néel state presents unique obstacles because of its vanishingly small net moment. In fact, because of the small moment in antiferromagnets MOKE investigations of them should be prohibited as the linear magneto-optical effect would normally be absent. Yet here we report the observation of a large MOKE signal in an antiferromagnet at room temperature. In particular, we find that having only a vanishingly small magnetization of less than 0.002 µB/Mn, the non-collinear antiferromagnet Mn3Sn exhibits a large zero-field MOKE with a polar Kerr rotation angle of nearly 20 milli- degrees, comparable to ferromagnetic metals. This large MOKE further allows real-time imaging of magnetic domains and their reversal under external magnetic fields. The extraordinarily large MOKE comes from the topological character of the electronic structure; this unusual character also leads to a large anomalous Hall effect. The observation of a large MOKE in non- collinear antiferromagnets should open
Citation: Nature Photonics
Pub Type: Journals

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Created January 26, 2018, Updated March 06, 2018