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Nonlinear optical effects in inversion-symmetry-breaking superconductors

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Abstract

We study nonlinear optical responses in superconducting systems with inversion (I) symmetry-breaking order parameters. We first show that any superconducting system with I and time-reversal (T) symmetries requires an I-breaking order parameter to support optical transitions between particle-hole pair bands. We then use a 1D toy model of an I-breaking superconductor to numerically calculate linear and nonlinear conductivities, including shift current and second harmonic generations (SHG) responses. We find that the magnitude of the signal is significantly larger in shift current/ SHG response than in the linear response due to the matrix element effect. We also present various scaling behaviors of the SHG signal, which may be relevant to the recent experimental observation of SHG in cuprates[1]. Finally, we confirm the generality of our observations regarding nonlinear responses of I-breaking superconductors, by analyzing other models including a 1D three-band model and 2D square lattice model.

[1] L. Zhao, C. A. Belvin, R. Liang, D. A. Bonn, W. N. Hardy, N. P. Armitage, and D. Hsieh, Nature Physics 13, 250–254 (2017)

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Presenters

  • Tianrui Xu

    Physics, University of California, Berkeley

Authors

  • Tianrui Xu

    Physics, University of California, Berkeley

  • Takahiro Morimoto

    Applied Physics, The University of Tokyo, Applied Physics, University of Tokyo, University of Tokyo, Univ of Tokyo, Applied physics department, University of Tokyo, The University of Tokyo

  • Joel Moore

    Physics, University of California, Berkeley, University of California, Berkeley