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arXiv · 2005.01105

Berry curvature for coupled waves of magnons and electromagnetic waves

Akihiro Okamoto·Ryuichi Shindou·Shuichi Murakami
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Abstract

In this paper, we introduce Berry curvature, topological Chern number and topological chiral edge mode, that emerge from a hybridization between magnon and electromagnetic wave in a ferromagnet insulator. By focusing on the energy conservation, we first reformulate the Landau-Lifshitz-Maxwell equation into a Hermitian eigenvalue equation. From the eigenvalue equation, we define the Berry curvature of the magnon-photon coupled waves. We show that the Berry curvature thus introduced shows a prominent peak around a hybridization point between magnon mode and photon mode, and a massive hybrid mode takes a non-zero Chern number ($\pm 1$) due to the magnon-photon coupling. In accordance with the non-zero Chern number, the topological edge modes emerge inside the hybridization gap at a domain wall between two ferromagnetic insulators with opposite magnetizations.

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Akihiro Okamoto, Ryuichi Shindou, Shuichi Murakami. 2020-05-03. Berry curvature for coupled waves of magnons and electromagnetic waves. https://doi.org/10.1103/physrevb.102.064419

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