关键词: FeSe基超导/
单晶生长/
薄膜生长/
超导性质
English Abstract
New progress of FeSe-based superconducting single crystals and films: Spin nematicity, electronic phase separation, and high critical parameters
Dong Xiao-Li1,2,Jin Kui1,2,
Yuan Jie1,2,
Zhou Fang1,2,
Zhang Guang-Ming3,
Zhao Zhong-Xian1,2
1.National Lab for Supreconductivity, Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China;
2.Key Laboratory for Vacuum Physics, University of Chinese Academy of Sciences, Beijing 100049, China;
3.State Key Laboratory of Low Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China
Fund Project:Project supported by the National Basic Research Program of China (Grant Nos. 2017YFA0303003, 2016YFA0300300), the National Natural Science Foundation of China (Grant No. 11574370), and the Strategic Priority Research Program and Key Research Program of Frontier Sciences of the Chinese Academy of Sciences (Grant Nos. QYZDY-SSW-SLH001, QYZDY-SSW-SLH008, XDB07020100).Received Date:03 September 2018
Accepted Date:25 September 2018
Published Online:20 October 2019
Abstract:High-quality superconducting single crystals and thin films play an important role in the basic research and application of high-Tc superconductivity. In these two aspects, iron-based superconductors feature the merit of rich physical phenomena and high superconducting critical parameters (including the transition temperature Tc, the upper critical field Hc2 and the critical current density Jc). By developing ion-exchange and ion-de-intercalation method, we successfully synthesize a series of high-quality and sizable (Li,Fe)OHFeSe and FeSe single crystal samples. We observe Ising spin nematicity (below Tsn), and the universal linear relationship between Tc and Tsn in FeSe single crystals, indicating that the superconductivity is closely related to the spin nematicity driven by stripe antiferromagnetic spin fluctuations. In (Li,Fe)OHFeSe single crystals, we observe the coexistence of an AFM state (below Tafm~125 K) together with the SC state. We explain the coexistence by electronic phase separation, similar to that in high-Tc cuprates and iron arsenides, and establish a complete phase diagram for (Li,Fe)OHFeSe system. Here, we also make a brief introduction about our latest progress in growing a high-quality single-crystalline superconducting film of (Li,Fe)OHFeSe. The film is prepared by a hydrothermal epitaxial method. The high crystalline quality of the film is demonstrated by x-ray diffraction results, showing a single (001) orientation with a small crystal mosaic of 0.22 in terms of the full width at half maximum of the rocking curve, as well as an excellent in-plane orientation by the -scan of (101) plane. Its bulk superconducting transition temperature Tc of 42.4 K is characterized by both zero electrical resistance and diamagnetization measurements. Based on systematic magnetoresistance measurements, the values of upper critical field Hc2 are estimated at 79.5 T and 443 T for the magnetic field perpendicular and parallel to the ab plane, respectively. Moreover, a large critical current density Jc of a value over 0.5 MA/cm2 is achieved at~20 K. Such a (Li,Fe)OHFeSe film is not only important for the fundamental research for understanding the high-Tc mechanism, but also promises the high-Tc superconductivity applications, especially in high-performance electronic devices and large scientific facilities such as superconducting accelerator.
Keywords: FeSe-based superconductor/
single crystal growth/
film growth/
superconducting properties
