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 

作者机构：Institute of Physics and Beijing National Laboratory for Condensed Matter PhysicsChinese Academy of SciencesBeijing 100190China Department of Physics and AstronomyUCIALos AngelesCA 90095USA Institute for High Pressure PhysicsRussian Academy of Sciences142190 TroitskMoscowRussia Shanghai Synchrotron Radiation FacilitiesShanghai Institute of Applied PhysicsChinese Academy of SciencesShanghai 201204China State Key Laboratory for Low Dimensional Quantum Physics and Department of PhysicsTsinghua UniversityBelting 100084China Collaborative Innovation Center of Quantum MatterBeijing 100190China University of Chinese Academy of SciencesBeijing 100190China 

出 版 物：《Science Bulletin》 (科学通报（英文版）)

年 卷 期：2017年第62卷第12期

页      面：857-862页

核心收录：

学科分类：080801[工学-电机与电器] 0808[工学-电气工程] 08[工学] 0805[工学-材料科学与工程（可授工学、理学学位）] 080502[工学-材料学] 

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) 

主　　题：超导单晶 反铁磁性 临界点 加压 磁转变温度 超导转变温度 高温超导体 相互作用 

摘      要：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.