Anomalous Higgs oscillations mediated by Berry curvature and quantum metric
Higgs spectroscopy, the study of Higgs bosons of a superconductor, is an emerging field in studying superconductivity. Here we show that the Berry curvature and the quantum metric of bands play a central role in the Higgs mode generation. They allow the detection of Higgs bosons even when the con...
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| Main Authors: | , |
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| Other Authors: | |
| Format: | Article |
| Language: | English |
| Published: |
2022
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| Subjects: | |
| Online Access: | https://hdl.handle.net/10356/156748 |
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| Institution: | Nanyang Technological University |
| Language: | English |
| Summary: | Higgs spectroscopy, the study of Higgs bosons of a superconductor, is an
emerging field in studying superconductivity. Here we show that the Berry
curvature and the quantum metric of bands play a central role in the Higgs mode
generation. They allow the detection of Higgs bosons even when the conventional
contribution from the band curvature vanishes. Furthermore, we show that the
Higgs mode can couple to the external electromagnetic field linearly when
mediated by the Berry connection. As a result, we predict the existence of a
second harmonic generation, in addition to the well-known third harmonic
generation. We elucidate our theory further by considering a flat band
superconductor realized by the Harper-Hubbard model and show that the geometric
Higgs mode is lower bounded by the band Chern number. We demonstrate in twisted
bilayer graphene the existence of the geometrically induced Higgs modes when
superconductivity is realized in the nearly flat band at the magic angle. |
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