Probing Berry Curvature in Magnetic Topological Insulators through Resonant Infrared Magnetic Circular Dichroism
Sprache des Titels:
Englisch
Original Kurzfassung:
Probing the quantum geometry and topology in condensed matter systems has relied heavily on static
electronic transport experiments in magnetic fields. Yet, contact-free optical measurements have rarely
been explored. Here, we report the observation of resonant magnetic circular dichroism (MCD) in the
infrared range in thin film MnBi2Te4 exhibiting a spectral intensity that correlates with the anomalous Hall
effect. Both phenomena emerge with a field-driven phase transition from an antiferromagnet to a canted
ferromagnet. By theoretically relating the MCD to the anomalous Hall effect via Berry curvature for a
metallic state, we show that this transition accompanies an abrupt onset of Berry curvature, signaling a
topological phase transition from a topological insulator to a doped Chern insulator. Our density functional
theory calculation suggests the MCD signal mainly originates from an optical transition at the Brillouin
zone edge, hinting at a potential new source of Berry curvature away from the commonly considered ?
point. Our findings demonstrate a novel experimental approach for detecting Berry curvature through
spectroscopy of the interband MCD, generally applicable to magnetic materials
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