Mapping the lattice-vibration potential using terahertz pulses

TL;DR

This paper introduces a method to map anharmonic lattice potentials in materials using terahertz pulses, accounting for substrate effects and broad-band pulse averaging, demonstrated on SrTiO3.

Contribution

The authors present a novel approach for reconstructing lattice potentials from terahertz pulse measurements, including substrate reflections and broadband effects.

Findings

Successfully applied to SrTiO3 ferroelectric soft-mode

Accurately accounts for substrate reflections in potential mapping

Provides a framework for experimental lattice potential reconstruction

Abstract

We develop a method for mapping the anharmonic lattice potential using the time-dependent electric field of the transmitted pulse through thin sample supported by a substrate of non-negligible thickness. Assuming linear propagation in the substrate we fully take into account internal reflection in it while the sample can show arbitrary nonlinear response. We examine the effect of frequency averaging appropriate for broad-band pulse and compare the results taking into account the full frequency dependence. We illustrate the procedure applying it to a model based on recently observed ferroelectric soft-mode nonlinearity in SrTiO$_3$.