Tuning electronic properties of FeSe 0.5 Te 0.5 thin flakes using a solid ion conductor field-effect transistor

作者：Chundong Zhu, Jianhua Cui, Bin Lei, N. Z. Wang, Chao Shang, Fanbao Meng, L. K. Ma, X. G. Luo, Tao Wu, Zhao‐Yan Sun, Xianhui Chen · 发表于：Physical review. B./Physical review. B · 年份：2017 · DOI：10.1103/physrevb.95.174513 · 被引用次数：26 · 研究领域：Iron-based superconductors research、Magnetic and transport properties of perovskites and related materials、Chalcogenide Semiconductor Thin Films

Using a field-effect transistor (FET) configuration with solid Li-ion conductor (SIC) as gate dielectric, we have successfully tuned carrier density in ${\mathrm{FeSe}}_{0.5}{\mathrm{Te}}_{0.5}$ thin flakes, and the electronic phase diagram has been mapped out. It is found that electron doping controlled by SIC-FET leads to a suppression of the superconducting phase, and eventually gives rise to an insulating state in ${\mathrm{FeSe}}_{0.5}{\mathrm{Te}}_{0.5}$. During the gating process, the (001) peak in x-ray diffraction patterns stays at the same position and no new diffraction peak emerges, indicating no evident ${\mathrm{Li}}^{+}$ ions intercalation into the ${\mathrm{FeSe}}_{0.5}{\mathrm{Te}}_{0.5}$. It indicates that a systematic change of electronic properties in ${\mathrm{FeSe}}_{0.5}{\mathrm{Te}}_{0.5}$ arises from the electrostatic doping induced by the accumulation of ${\mathrm{Li}}^{+}$ ions at the interface between ${\mathrm{FeSe}}_{0.5}{\mathrm{Te}}_{0.5}$ and solid ion conductor in the devices. It is striking that these findings are drastically different from the observation in FeSe thin flakes using the same SIC-FET, in which ${T}_{c}$ is enhanced from 8 K to larger than 40 K, then the system goes into an insulating phase accompanied by structural transitions.