Publications Repository - Helmholtz-Zentrum Dresden-Rossendorf

In spectroscopy studies of solids, interaction between a discrete mode and a continuum of excitations sometimes leads to an interference effect known as the Fano resonance, characterized by the asymmetric scattering amplitude of the discrete mode as a function of electromagnetic driving frequency. Cuprate high-Tc superconductors are known for its intertwined interactions and the coexistence of competing orders. In this study, we report a new type of Fano resonance manifested by the collective amplitude oscillations of the superconducting order, i.e. the Higgs mode, in cuprate high-Tc superconductors, where we resolve both the amplitude and phase signatures of the Fano resonance. Our observation suggests that the heavily damped Higgs mode is coupled to another collective mode in the system. Based on the results of an extensive hole-doping and magnetic field dependent investigation, we speculate charge density wave fluctuations as the coupled mode. Our study highlights the possibility of a dynamical interaction between superconductivity and charge density wave in cuprate high-Tc superconductors, which demonstrates the scientific prospect of Higgs spectroscopy as a new type of spectroscopy method.