Resonant enhancement of photo-induced superconductivity in K3C60
Elizabeth S. Rowe, Bo Yuan, M. Buzzi, Gregor Jotzu, Y. Zhu, M. Fechner, M. Först, B. Liu, Daniele Pontiroli, Mauro Riccò, A. Cavalleri
Abstract
Abstract Photo-excitation at terahertz and mid-infrared frequencies has emerged as an effective way to manipulate functionalities in quantum materials, in some cases creating non-equilibrium phases that have no equilibrium analogue. In K 3 C 60 , a metastable zero-resistance phase was observed that has optical properties, nonlinear electrical transport and pressure dependencies compatible with non-equilibrium high-temperature superconductivity. Here we demonstrate a two-orders-of-magnitude increase in photo-susceptibility near 10 THz excitation frequency. At these drive frequencies, a metastable superconducting-like phase is observed up to room temperature. The discovery of a dominant frequency scale sheds light on the microscopic mechanism underlying photo-induced superconductivity. It also indicates a path towards steady-state operation, limited at present by the availability of a suitable high-repetition-rate optical source at these frequencies.