Observation of a bi-critical point between antiferromagnetic and superconducting phases in pressurized single crystal Ca0.73La0.27FeAs2  

作　　者：Yazhou Zhou ShanJiang Qi wu Vladimir A.Sidorov Jing Guo Wei Yi Shan Zhang Zhe Wang HonghongWang shu Cai Ke Yang Sheng Jiang Aiguo Li Ni Ni Guangming Zhang Liling Sun Zhongxian Zhao 

机构地区：[1]Institute of Physics and Beijing National Laboratory for Condensed Matter Physics,Chinese Academy of Sciences,Beijing 100190,China [2]Department of Physics and Astronomy,UCIA,Los Angeles,CA 90095,USA [3]Institute for High Pressure Physics,Russian Academy of Sciences,142190 Troitsk,Moscow,Russia [4]Shanghai Synchrotron Radiation Facilities,Shanghai Institute of Applied Physics,Chinese Academy of Sciences,Shanghai 201204,China [5]State Key Laboratory for Low Dimensional Quantum Physics and Department of Physics,Tsinghua University,Belting 100084,China [6]Collaborative Innovation Center of Quantum Matter,Beijing 100190,China [7]University of Chinese Academy of Sciences,Beijing 100190,China

出　　处：《Science Bulletin》2017年第12期857-862,共6页科学通报（英文版）

基　　金：supported by the National Natural Science Foundation of China(91321207,11427805,U1532267,11404384);the Strategic Priority Research Program(B)of the Chinese Academy of Sciences(XDB07020300);the National Key Research and Development Program of China(2016YFA0300300);the Russian Foundation for Basic Research(15-02-02040);the U.S.NSF DMREF(DMR-1435672)

摘　　要：One of the most strikingly universal features of the high-temperature superconductors is that the super- conducting phase emerges in the close proximity of the antiferromagnetic phase, and the interplay between these two phases poses a long-standing challenge. It is commonly believed that, as the antifer- romagnetic transition temperature is continuously suppressed to zero, there appears a quantum critical point, around which the existence of antiferromagnetic fluctuation is responsible for the development of the superconductivity. In contrast to this scenario, we report the observation of a bi-critical point identified at 2,88 GPa and 26.02 K in the pressurized high-quality single crystal Cao.73Lao.27FeAs2 by com- plementary in-situ high pressure measurements. At the critical pressure, we find that the antiferromag- netism suddenly disappears and superconductivity simultaneously emerges at almost the same temperature, and that the external magnetic field suppresses the superconducting transition temperature but hardly affects the antiferromagnetic transition temperature.One of the most strikingly universal features of the high-temperature superconductors is that the superconducting phase emerges in the close proximity of the antiferromagnetic phase, and the interplay between these two phases poses a long-standing challenge. It is commonly believed that, as the antiferromagnetic transition temperature is continuously suppressed to zero, there appears a quantum critical point, around which the existence of antiferromagnetic fluctuation is responsible for the development of the superconductivity. In contrast to this scenario, we report the observation of a bi-critical point identified at 2.88 GPa and 26.02 K in the pressurized high-quality single crystal Ca_(0.73)La_(0.27)FeAs_2 by complementary in-situ high pressure measurements. At the critical pressure, we find that the antiferromagnetism suddenly disappears and superconductivity simultaneously emerges at almost the same temperature, and that the external magnetic field suppresses the superconducting transition temperature but hardly affects the antiferromagnetic transition temperature.

关 键 词：Iron pnictide superconductorBi-critical pointSuperconductivityAntiferromagnetic orderHigh pressure 

分 类 号：TM26[一般工业技术—材料科学与工程]