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Collinear Anomalous Hall Antiferromagnets

Date : Wednesday, December 5th, 2018 11:00 am - 12:00 pm Place : Seminar Room 5 (A615), 6th Floor, ISSP Lecturer : Dr. Hua Chen Affiliation : Department of Physics, Colorado State University Committee Chair : Satoru Nakatsuji (内)63240)
e-mail: satoru@issp.u-tokyo.ac.jp

It is now well established both theoretically and experimentally that the anomalous Hall effect (AHE) can exist in certain noncollinear antiferromagnets with vanishing total magnetization. Using similar symmetry arguments, we propose that the AHE and many related properties such as magneto-optical Kerr effect, anomalous Nernst effect, orbital magnetization, etc., can also exist in many collinear antiferromagnets with symmetry-allowed spin canting. Similar to the noncollinear case, these AHE-related effects will still be finite when the net spin magnetization vanishes. We give two classic examples, NiF2 and alpha-Fe2O3, corresponding to different mechanisms for spin canting, i.e. single-ion anisotropy and Dzyaloshinskii-Moriya interaction. Although these two materials are good insulators and may not be easily doped in order to measure the AHE, the discussion is general and can be applied to many other canted antiferromagnets. We construct minimal models with spin-orbit coupling terms compatible with these canting mechanisms and discuss the similarities and differences between the collinear and the noncollinear cases.

 


(Published on: Monday November 26th, 2018)