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arXiv · 2501.14138

Time-reversal symmetry breaking, collective modes, and Raman spectrum in pair-density-wave states

Yi-Ming Wu·Andrey V. Chubukov·Yuxuan Wang·Steven A. Kivelson
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Abstract

Inspired by empirical evidence of the existence of pair-density-wave (PDW) order in certain underdoped cuprates, we investigate the collective modes in systems with unidirectional PDW order with momenta $\pm {Q}$ and a $d$-wave form-factor with special focus on the amplitude (Higgs) modes. In the pure PDW state, there are two overdamped Higgs modes. We show that a phase with co-existing PDW and uniform ($d$-wave) superconducting (SC) order, PDW/SC, spontaneously breaks time-reversal symmetry - and thus is distinct from a simpler phase, SC/CDW, with coexisting SC and charge-density-wave (CDW) order. The PDW/SC phase exhibits three Higgs modes, one of which is sharply peaked and is predominantly a PDW fluctuation, symmetric between ${Q}$ and -${Q}$, whose damping rate is strongly reduced by SC. This sharp mode should be visible in Raman experiments.

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Yi-Ming Wu, Andrey V. Chubukov, Yuxuan Wang, Steven A. Kivelson. 2025-01-23. Time-reversal symmetry breaking, collective modes, and Raman spectrum in pair-density-wave states. https://arxiv.org/abs/2501.14138

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