Special CPM Seminar

Shedding light on collective modes in two-dimensional superconductors

Ben Levitan

Weizmann Institute

Fluctuations of superconducting order give rise to a rich diversity of collective modes, depending on the structure of the pairing state and the underlying interactions. Collective mode spectroscopy can therefore be a powerful tool in the study of unconventional superconductors. However, symmetries frequently forbid coupling of long-wavelength light to exotic collective modes, complicating the detection of those modes. I will show how working in low dimensions can provide powerful workarounds to these challenges. As an illustrative case study, I will show how all-electronic pairing mechanisms could produce an in-gap clapping mode in superconducting rhombohedral trilayer graphene (RTG). The superconducting phases of RTG (and other emerging materials) are stabilized by a displacement field, applied by gate electrodes; I will show how those same electrodes could be used to detect the clapping mode. Our results point towards a particularly convenient method for collective-mode spectroscopy of gated low-dimensional superconductors.

[1] B. A. Levitan, Y. Oreg, E. Berg, M. S. Rudner, and I. Iorsh. Linear spectroscopy of collective modes and the gap structure in two-dimensional superconductors. arXiv:2406.08706