# Ultrafast x-ray diffraction probe of terahertz field-driven soft mode dynamics

## TL;DR

This study employs ultrafast x-ray diffraction to investigate how strong terahertz fields influence the soft optical phonon modes in SrTiO3, revealing transient lattice dynamics and temperature-dependent softening of specific modes.

## Contribution

It demonstrates the use of ultrafast x-ray diffraction to directly observe terahertz-driven soft mode dynamics in a complex oxide material.

## Key findings

- Transient diffraction intensity changes with delayed onset
- Identification of two frequency components in lattice response
- Softening of the lower frequency mode at lower temperatures

## Abstract

We use ultrafast x-ray pulses to characterize the lattice response of SrTiO3 when driven by strong terahertz (THz) fields. We observe transient changes in the diffraction intensity with a delayed onset with respect to the driving field. Fourier analysis reveals two frequency components corresponding to the two lowest energy zone-center optical modes in SrTiO3. The lower frequency mode exhibits clear softening as the temperature is decreased while the higher frequency mode shows slight temperature dependence.

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Source: https://tomesphere.com/paper/1703.09818