paper

Ionic-liquid-gating induced protonation and superconductivity in FeSe, FeSe0.93S0.07, ZrNCl, 1T-TaS2, and Bi2Se3

arXiv:1905.10080 · doi:10.1088/0256-307X/36/7/077401

Abstract

We report protonation in several compounds by an ionic-liquid-gating method, with optimized gating conditions. This leads to single superconducting phases for several compounds. Non-volatility of protons allow post-gating magnetization and transport measurements. The superconducting transition temperature $T_{C}$ is enhanced to 43.5~K for FeSe $_{0.93}$ S $_{0.07}$ , and 41~K for FeSe after protonation. Superconductivity with $T_{c}$ $\approx$ 15~K for ZrNCl, $\approx$ 7.2~K for 1 $T$ -TaS $_{2}$ , and $\approx$ 3.8~K for Bi $_{2}$ Se $_{3}$ are induced after protonation. Electric transport in protonated FeSe $_{0.93}$ S $_{0.07}$ confirms high-temperature superconductivity. Our $^{1}$ H NMR measurements on protonated FeSe $_{1 - x}$ S $_{x}$ reveal enhanced spin-lattice relaxation rate $1 /^{1} T_{1}$ with increasing $x$ , which is consistent with LDA calculations that H $^{+}$ are located in the interstitial sites close to the anions.

4 pages, 7 figures