Higgs Spectroscopy measures the interplay of superconductiv­ity and charge density waves via Fano-interference

Superconductivity is a fascinating state of solid-state physics and describes a perfect conductor and perfect diamagnet. Especially in unconventional superconductors, superconductivity is in a complicated interplay with other orders. A well-known example is a charge density wave in cuprate superconductors. Now, for the first time, we have succeeded in measuring the interplay of these orders within the framework of Higgs spectroscopy.

For this purpose, the superconducting order is excited with strong THz pulses to so-called Higgs oscillations, the collective oscillations of the superconductor. In the experiment, an interaction of the superconductivity with the charge density wave is now revealed by a characteristic spectroscopic signature: The Fano resonance characterizes the interaction of the superconducting and charge density order by its asymmetric line shape for the first time in one experiment, without the need to measure these orders in different experiments.

Hao Chu, Sergey Kovalev, Zi Xiao Wang, Lukas Schwarz, Tao Dong, Liwen Feng, Rafael Haenel, Min-Jae Kim, Parmida Shabestari, Le Phuong Hoang, Kedar Honasoge, Robert David Dawson, Daniel Putzky, Gideok Kim, Matteo Puviani, Min Chen, Nilesh Awari, Alexey N. Ponomaryov, Igor Ilyakov, Martin Bluschke, Fabio Boschini, Marta Zonno, Sergey Zhdanovich, Mengxing Na, Georg Christiani, Gennady Logvenov, David J. Jones, Andrea Damascelli, Matteo Minola, Bernhard Keimer, Dirk Manske, Nanlin Wang, Jan-Christoph Deinert & Stefan Kaiser . Fano interference between collective modes in cuprate high-T_c superconductors. Nat Commun 14, 1343 (2023). https://doi.org/10.1038/s41467-023-36787-4