We report on an ultrafast photoinduced phase transition with a strikingly long-lived Martensitic anomaly driven by above-threshold single-cycle terahertz (THz) pulses in Nb3Sn. A non-thermal, THz-induced depletion of low frequency conductivity indicates increased gap splitting of high energy Γ12 bands by removal of their degeneracies which enhances the Martensitic phase. In contrast, optical pumping leads to a Γ12 gap melting. Such light-induced non-equilibrium Martensitic instability persists up to a critical temperature ∼100 K, i.e., more than twice the equilibrium temperature, and can be stabilized beyond technologically-relevant, nanosecond timescales. Together with first-principle simulations, we identify a compelling THz tuning of structural fluctuations via Eu phonons to achieve a non-equilibrium ordering at high temperatures far exceeding those for equilibrium states.
@article{arxiv.2008.08732,
title = {Discovery of Light-induced Metastable Martensitic Anomaly Controlled by Single-Cycle Terahertz Pulses},
author = {X. Yang and B. Song and C. Vaswani and L. Luo and C. Sundahl and M. Mootz and J-H. Kang and Y. Yao and K-M Ho and I. E. Perakis and C. B. Eom and J. Wang},
journal= {arXiv preprint arXiv:2008.08732},
year = {2020}
}