Optical manipulation of coherent phonons in superconducting YBa2Cu3O7−δ thin films

Abstract

The coherent phonons of YBa₂Cu₃O_7−δ are believed to be strongly coupled to its superconductivity. Controlling the phonons below its transition temperature, therefore, may serve as a promising scheme of the control of superconductivity. Here we demonstrate optical manipulation of the Ba–O and Cu–O vibrations in a thin-film YBa₂Cu₃O_7−δ below its transition temperature using a pair of femtosecond laser pulses. The interpulse delay is tuned to integral and half-integral multiples of the oscillation period of a specific phonon mode (Ba–O or Cu–O vibration) to enhance and suppress its amplitude, respectively.