Terahertz (THz) radiation with its spectrum extending up to 1 THz has been observed by an illumination of femtosecond optical pulses to optical switching devices fabricated on magnetoresistive manganite thin films; Pr0.7Ca0.3MnO3. The THz radiation strongly depends on temperature T and its T trend reverses sign across charge-orbital and spin ordering T's.
@article{arxiv.cond-mat/0008298,
title = {Terahertz radiation from magnetoresistive Pr$_{\text{0.7}}$Ca$_{\text{0.3}}$MnO$_{\text3}$ thin films},
author = {N. Kida and M. Tonouchi},
journal= {arXiv preprint arXiv:cond-mat/0008298},
year = {2009}
}