Superconductivity in the bilayer nickelate ${\mathrm{La}}_3{\mathrm{Ni}}_2{\mathrm{O}}_7$ 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 ${\mathrm{La}}_3{\mathrm{Ni}}_2{\mathrm{O}}_7$ 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 ${\mathrm{La}}_3{\mathrm{Ni}}_2{\mathrm{O}}_7$.

Close

PrevNext

View figure in article

• Lattice dynamics
• Optical & microwave phenomena
• Optical phonons
• Superconductivity
• Nickelates
• Strongly correlated systems
• Superconductors
• Density functional theory