The charge and spin dynamics of the structurally simplest iron-based superconductor, FeSe, may hold the key to understanding the physics of high temperature superconductors in general. Unlike the iron pnictides, FeSe lacks long range magnetic order in spite of a similar structural transition around 90\,K. Here, we report results of Raman scattering experiments as a function of temperature and polarization and simulations based on exact diagonalization of a frustrated spin model. Both experiment and theory find a persistent low energy peak close to 500cm−1 in B1g symmetry, which softens slightly around 100\,K, that we assign to spin excitations. By comparing with results from neutron scattering, this study provides evidence for nearly frustrated stripe order in FeSe.
@article{arxiv.1709.08998,
title = {Frustrated spin order and stripe fluctuations in FeSe},
author = {Andreas Baum and Harrison N. Ruiz and Nenad Lazarević and Yao Wang and Thomas Böhm and Ramez Hosseinian Ahangharnejhad and Peter Adelmann and Thomas Wolf and Zoran V. Popović and Brian Moritz and Thomas P. Devereaux and Rudi Hackl},
journal= {arXiv preprint arXiv:1709.08998},
year = {2019}
}