Nonlinear phononics in LaFeAsO: Optical control of the crystal structure toward possible enhancement of superconductivity

TL;DR

This study explores how nonlinear phononics can be used to optically manipulate the crystal structure of LaFeAsO, an iron-based superconductor, to potentially improve its superconducting properties.

Contribution

It demonstrates, through simulations, that selective excitation of infrared-active phonons can tune the anion height toward an optimal value for superconductivity.

Findings

Anion height approaches the ideal value when specific phonons are excited.

Simulation results suggest structural control via light can enhance superconductivity.

Nonlinear phononics offers a pathway to manipulate superconductor properties.

Abstract

Nonlinear phononics provides a route to control crystal structures through light-induced phonon excitation. In this study, we apply nonlinear phononics to an iron-based superconductor, LaFeAsO, with the aim of tuning its crystal structure toward the ideal one to enhance superconductivity. We simulate light-induced phonon dynamics on the anharmonic lattice potential determined by first-principles calculations. We find that the anion height $h$, a key structural parameter in iron-based superconductors, approaches its ideal value when an appropriate infrared-active phonon mode is selectively excited. This result suggests the possibility of controlling crystal structures and enhancing superconductivity in iron-based superconductors based on the concept of nonlinear phononics.