Optical control of the crystal structure in the bilayer nickelate superconductor La3Ni2O7 via nonlinear phononics

Abstract

Superconductivity in the bilayer nickelate La3Ni2O7 occurs when the interlayer Ni-O-Ni bond angle becomes straight under pressure, suggesting a strong relationship between the crystal structure and the emergence of superconductivity. In this study, we theoretically propose a way to control the crystal structure of La3Ni2O7 toward the tetragonal symmetry via light irradiation instead of pressure using the idea of nonlinear phononics. Here, resonant optical excitation of an infrared-active (IR) lattice vibration induces a nonlinear Raman-mode displacement through the anharmonic phonon-phonon coupling. We calculate the light-induced phonon dynamics on the anharmonic lattice potential determined by first-principles calculation. We find that the interlayer Ni-O-Ni bond angle gets slightly closer to straight when an appropriate IR mode is selectively excited. Our study suggests that light irradiation can be a promising way for structural control of La3Ni2O7.

Source-reported materials — not catalogue approval

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