paper

Spatially-resolved dynamics of the amplitude Schmid-Higgs mode in disordered superconductors

arXiv:2409.11647 · doi:10.1103/x12p-q7bj

Abstract

We investigate the spatially-resolved dynamics of the collective amplitude Schmid-Higgs (SH) mode in disordered -wave superconductors and fermionic superfluids. By analyzing the analytic structure of the zero-temperature SH susceptibility in the complex frequency plane, we find that when the coherence length greatly exceeds the mean free path: (i) the SH response at fixed wave vectors exhibits late-time oscillations decaying as with frequency , where is the superconducting gap; (ii) sub-diffusive oscillations with a dynamical exponent emerge at late times and large distances; and (iii) spatial oscillations at fixed frequency decay exponentially, with a period that diverges as the frequency approaches from above. When the coherence length is comparable to the mean free path, additional exponentially-decaying oscillations at fixed wave vectors appear with frequency above . Furthermore, we show that the SH mode induces an extra peak in the third-harmonic generation current at finite wave-vectors. The frequency of this peak is shifted from the conventional resonance at , thereby providing an unambiguous signature of order parameter amplitude dynamics.

v3, 4.5+1.5+10 pages, 3+3 figures

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