Ultrafast optical pump-probe spectroscopy is used to track carrier dynamics in the large magnetoresistance material WTe2. Our experiments reveal a fast relaxation process occurring on a sub-picosecond time scale that is caused by electron-phonon thermalization, allowing us to extract the electron-phonon coupling constant. An additional slower relaxation process, occurring on a time scale of ∼5-15 picoseconds, is attributed to phonon-assisted electron-hole recombination. As the temperature decreases from 300 K, the timescale governing this process increases due to the reduction of the phonon population. However, below ∼50 K, an unusual decrease of the recombination time sets in, most likely due to a change in the electronic structure that has been linked to the large magnetoresistance observed in this material.
@article{arxiv.1506.07601,
title = {Ultrafast Carrier Dynamics in the Large Magnetoresistance Material WTe$_{2}$},
author = {Y. M. Dai and J. Bowlan and H. Li and H. Miao and S. F. Wu and W. D. Kong and Y. G. Shi and S. A. Trugman and J. -X. Zhu and H. Ding and A. J. Taylor and D. A. Yarotski and R. P. Prasankumar},
journal= {arXiv preprint arXiv:1506.07601},
year = {2015}
}