In this talk, we report on our recent progress of novel routes for exploring high-Tc superconductors in FeSe-derived compounds. Firstly, we synthesized an air-stable material, (Li0.8Fe0.2)OHFeSe, which shows superconducting transition temperature up Tc to ~40 K, by means of a novel hydrothermal method. The crystal structure is unambiguously determined by a combination of X-ray and neutron powder diffraction and nuclear magnetic resonance. Moreover, antiferromagnetic order is found to coexist with superconductivity. Secondly, we realized high Tc with a maximum up to 43 K in single crystals of (Li,Fe)OHFeSe (with initial Tc~25 K), by liquid-ionic gating technique in the thin flakes of single crystal, and observed a striking first-order transition from superconductor to AFM insulator on the strong charge doping region, just at the verge of optimal doping with highest Tc. We also performed electron doping by liquid-ionic-gating technique in FeSe thin flake and achieved an enhancement of Tc up to 48 K (from initially ~10K) with continuously increasing the gate voltage to about 4.2 V. At some certain carrier concentration, a Lifshitz transition was suggested as the sample suddenly changed from low-Tc to high-Tc phase. These results could help researchers to pursuit new path for exploring higher Tc in these materials.
陈仙辉，1992年博士毕业于中国科学技术大学物理系，中国科学技术大学教授。曾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做洪堡学者，先后在日本高等研究院(北陆)、美国休斯敦大学德克萨斯超导研究中心、新加坡国立大学做访问教授。主要从事高温超导体材料、强关联体系以及其它新型功能材料的探索合成和物理性质的研究。迄今发表文章300余篇，包括国际高水平杂志如Nature、Science、Nature Materials、Nature Nanotechnol.、Nature Phys.、Nature Commun.、Phys. Rev. Lett.、J. Am. Chem. Soc.等, 论文被他引近9000次，单篇最高他引超过1000次。应邀担任《Solid State Commun.》、《Scientific reports》、《SCIENCE CHINA Materials》编委，《物理》、《物理学进展》编委。1998年获国家杰出青年科学基金，2002年教育部长江特聘教授，2009年获中国物理学会叶企孙奖、2009年获长江学者成就奖，2009年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Bernd T. Matthias Prize。
邀请人：贾金锋 jfjia@sjtu.edu.cn