中国科学技术大学物理系
中科院强耦合量子材料物理重点实验室

报告人简介：
陈仙辉教授，1992年在中国科学技术大学获博士学位。现为中国科学技术大学教授，中国科学院院士，中科院强耦合量子材料物理重点实验室主任。曾先后作为洪堡学者和访问学者在德国卡尔斯鲁厄研究中心和斯图加特马普固体物理研究所、日本高等研究院(北陆)、美国休斯敦大学德克萨斯超导研究中心以及新加坡国立大学访问工作。1998年获国家杰出青年基金，2002年获聘教育部“长江学者”特聘教授。主要研究方向为超导等新型功能材料和强关联电子体系材料的探索及其物理研究。陈仙辉已在《自然》（4篇）、《科学》（1篇）《自然》子刊（18篇）和《物理评论快报》（35篇）等刊物发表SCI论文370余篇，总引用15000余次，其中单篇最高引用2100余次。2008年获教育部和李嘉诚基金会―长江学者成就奖，2009年获中国物理学会―叶企孙奖，2009年获香港求是科技基金会―求是杰出科技成就集体奖，2013年获国家自然科学一等奖，2015年获国际超导材料最高奖Bernd T. Matthias奖, 2017年获何梁何利基金科学与技术进步奖等。

报告摘要:
Electric field is adopted to control physical performance via tuning the carrier density. Such controllability through an electrostatic doping greatly promotes the development of research and industry for semiconductor. However, conventional metal-insulator-semiconductor (MIS) FET can only sustain very limited carrier density, and cannot meet further demands, especially in exploring high temperature superconductivity. Consequently, researchers attempt to seek for FET with new gate dielectric, such as the electric double layer FET (EDL-FET) based on liquid ions to break this bottleneck. In this talk, we report high temperature superconductivity with an onset above 40 K can be achieved in FeSe thin flake with Tc less than 10 K by tuning carrier with this EDL-FET technique. We also report on a novel FET device using solid ion conductor (SIC) as a gate dielectric, developed by our group, to overcome the inherent drawbacks of both MIS- and EDL-FET devices. Based on this SIC-FET technique, we achieved an optimal Tc of 46 K in FeSe thin flakes. A superconductivity-insulating state transition is observed. Two new metastable structures of Li_xFe₂Se₂ are obtained due to the Li intercalation driven by electrical field. A discrete superconducting phase diagram is observed in Li_xFeSe system. We also study the phase diagram of FeSe_0.5Te_0.5 and Bi₂Se₃ using SIC-FET. Li can be drove into/out the crystal based on the FET device using solid Li ion conductor as a gate dielectric, and many novel metastable structures can be obtained, consequently a series of phase transitions take place in (Li,Fe)OHFeSe and MoS₂. These phase transitions are reversible.

联系人：王玉鹏研究员（8264 9345）