关键词: RbCr3As3/
极低温热导率/
超导能隙
English Abstract
Superconducting gap of quasi-one-dimensional Cr-based superconductor RbCr3As3
Li Qing1,Wang Min-Xiang1,
Liu Tong2,
Mu Qing-Ge2,
Ren Zhi-An2,
Li Shi-Yan1
1.State Key Laboratory of Surface Physics, Department of Physics, Laboratory of Advanced Materials, Fudan University, Shanghai 200438, China;
2.Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
Fund Project:Project supported by the National Key Research and Development Plan of China (Grant Nos. 2016YFA0300503, 2015CB921401), the Joint Fund of the National Natural Science Foundation of China and the China Academy of Engineering Physics (Grant No. U1630248), and the National Natural Science Foundation of China (Grant Nos. 11474339, 11774402).Received Date:11 September 2018
Accepted Date:08 October 2018
Published Online:20 October 2019
Abstract:Since the discovery of high-temperature superconductivity in cuprates, finding more unconventional superconductors and understanding their superconducting pairing mechanism has been an important theme in condensed matter physics. Recently, ternary Cr-based superconductors A2Cr3As3 (A=K, Rb, Cs) and ACr3As3 (A=K, Rb) were reported, which own quasi-one-dimensional crystal structure, containing[(Cr3As3)-] linear chains. A2Cr3As3 belongs to P6m2 space group, and ACr3As3 crystallizes in a centrosymmetric structure with the space group P63/m. Many experiments, such as nuclear magnetic resonance, London penetration depth, show that A2Cr3As3 is an unconventional superconductor. However, these A2Cr3As3 compounds are extremely unstable in air. Here, we study the superconducting gap of the air-stable RbCr3As3 single crystal, using ultralow-temperature thermal conductivity measurement. The resistivity of RbCr3As3 single crystal shows a superconducting transition temperature Tczero at 6.6 K. The normal-state resistivity data from 20 K to 8 K are fitted to (T)=0 + AT2, which gives a residual resistivity of 0=781 cm. Then, the thermal conductivity of RbCr3As3 single crystal is measured at temperature down to 80 mK and in magnetic fields up to 9 T. In zero field, residual linear term 0/T=7.5 WK-2cm-1 is observed, which is about 24% of its normal-state value, suggesting nodes in the superconducting gap. At low field, the 0/T of RbCr3As3 shows a relatively faster field dependence than single-gap s-wave superconductors. These results reveal that RbCr3As3 is likely an unconventional superconductor with superconducting gap nodes, although the exact superconducting gap symmetry and structure for this quasi-one-dimensional superconductor needs further investigation.
Keywords: RbCr3As3/
ultralow-temperature thermal conductivity/
superconducting gap
