准一维Cr基超导体RbCr3As3的超导能隙

李青; 汪旻祥; 刘通; 穆青隔; 任治安; 李世燕

doi:10.7498/aps.67.20181692

摘要

RbCr3As3是具有[（Cr3As3）-]线性链的准一维超导体，超导转变温度约为6.6 K.对RbCr3As3单晶进行了电输运和极低温热输运性质的研究.低温下，拟合了RbCr3As3正常态电阻率随温度的变化，发现其满足费米液体行为.通过拟合超导转变温度随磁场的关系，得到RbCr3As3单晶的上临界场约为25.6 T.对RbCr3As3进行了零场下的极低温热导率测量，得到其剩余线性项为7.5 WK-2cm-1，占正常态热导率值的24%.测量不同磁场下RbCr3As3的热导率，发现与单带s波超导体相比较，RbCr3As3剩余线性项随磁场增加相对较快.这些结果表明RbCr3As3单晶很可能是有节点的非常规超导体.

关键词:

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

作者及机构信息

1.
复旦大学物理系, 应用表面物理国家重点实验室, 先进材料实验室, 上海 200438;

2.
中国科学院物理研究所, 北京凝聚态物理国家研究中心, 北京 100190

通信作者: 李世燕, shiyan_li@fudan.edu.cn

基金项目: 国家重点研发计划（批准号：2016YFA0300503，2015CB921401）、国家自然科学基金委员会-中国工程物理研究院联合基金（批准号：U1630248）和国家自然科学基金（批准号：11474339，11774402）资助的课题.

Authors and contacts

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

Corresponding author: Li Shi-Yan, shiyan_li@fudan.edu.cn

Funds: 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).

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[31]	Kuroki K, Arita R, Aoki H 2001 Phys. Rev. B 63 094509
[32]	Lebed A G 2012 Physica B 407 1803

施引文献

[1]	Norman M R 2011 Science 322 196
[2]	Voit J 1994 Rep. Prog. Phys. 57 977
[3]	Grner G 1988 Rev. Mod. Phys. 60 1129
[4]	Lee I J, Brown S E, Clark W G, Strouse M J, Naughton M J, Kang W, Chaikin P M 2001 Phys. Rev. Lett. 88 017004
[5]	Sepper O, Lebed A G 2013 Phys. Rev. B 87 100511
[6]	Bao J K, Liu J Y, Ma C W, Meng Z H, Tang Z T, Sun Y L, Zhai H F, Jiang H, Bai H, Feng C M, Xu Z A, Cao G H 2015 Phys. Rev. X 5 011013
[7]	Tang Z T, Bao J K, Liu Y, Sun Y L, Ablimit A, Zhai H F, Jiang H, Feng C M, Xu Z A, Cao G H 2015 Phys. Rev. B 91 020506
[8]	Tang Z T, Bao J K, Wang Z, Bai H, Jiang H, Liu Y, Zhai H F, Feng C M, Xu Z A, Cao G H 2015 Sci. China: Mater. 58 16
[9]	Zhou Y, Cao C, Zhang F C 2017 Sci. Bull. 62 208
[10]	Jiang H, Cao G H, Cao C 2015 Sci. Rep. 5 16054
[11]	Zhi H Z, Imai T, Ning F L, Bao J K, Cao G H 2015 Phys. Rev. Lett. 114 147004
[12]	Tang Z T, Bao J K，Liu Y, Bai H, Jiang H, Zhai H F, Feng C M, Xu Z A, Cao G H 2015 Sci. China: Mater. 58 543
[13]	Bao J K, Li L, Tang Z T, Liu Y, Li Y K, Bai H, Feng C M, Xu Z A, Cao G H 2015 Phys. Rev. B 91 180404
[14]	Mu Q G, Ruan B B, Pan B J, Liu T, Yu J, Zhao K, Chen G F, Ren Z A 2017 Phys. Rev. B 96 140504
[15]	Liu T, Mu Q G, Pan B J, Yu J, Ruan B B, Zhao K, Chen G F, Ren Z A 2017 Europhys. Lett. 120 27006
[16]	Shakeripour H, Petrovic C, Taillefer L 2009 New J. Phys. 11 055065
[17]	Sutherland M, Hawthorn D G, Hill R W, Ronning F, Wakimoto S, Zhang H, Proust C, Boaknin E, Lupien C, Taillefer L, Liang R X, Bonn D A, Hardy W N, Gagnon R, Hussey N E, Kimura T, Nohara M, Takagi H 2003 Phys. Rev. B 67 174520
[18]	Li S Y, Bonnemaison J B, Payeur A, Fournier P, Wang C H, Chen X H, Taillefer L 2008 Phys. Rev. B 77 134501
[19]	Dong J K, Zhou S Y, Guan T Y, Zhang H, Dai Y F, Qiu X, Wang X F, He Y, Chen X H, Li S Y 2010 Phys. Rev. Lett. 104 087005
[20]	Proust C, Boaknin E, Hill R W, Taillefer L, Mackenzie A P 2002 Phys. Rev. Lett. 89 147003
[21]	Suzuki M, Tanatar M A, Kikugawa N, Mao Z Q, Maeno Y, Ishiguro T 2002 Phys. Rev. Lett. 88 227004
[22]	Lowell J, Sousa J B 1970 J. Low. Temp. Phys. 3 65
[23]	Willis J, Ginsberg D 1976 Phys. Rev. B 14 1916
[24]	Boaknin E, Tanatar M A, Paglione J, Hawthorn D, Ronning F, Hill R W, Sutherland M, Taillefer L, Sonier J, Hayden S M, Brill J W 2003 Phys. Rev. Lett. 90 117003
[25]	Reid J P, Tanatar M A, Fecteau A J, Gordon R T, de Cotret S R, Leyraud N D, Saito T, Fukazawa H, Kohori Y, Kihou K, Lee C H, Iyo A, Eisaki H, Prozorov R, Taillefer L 2012 Phys. Rev. Lett. 109 087001
[26]	Lee I J, Chow D S, Clark W G, Strouse M J, Naughton M J, Chaikin P M, Brown S E 2003 Phys. Rev. B 68 092510
[27]	Belin S, Behnia K 1997 Phys. Rev. Lett. 79 2125
[28]	Luke G M, Rovers M T, Fukaya A, Gat I M, Larkin I，Savici A, Uemura Y J, Kojima K M, Chaikin P M, Lee I J, Naughton M J 2003 Physica B 326 378
[29]	Yonezawa S, MaenoY, Bechgaard K, Jrome D 2012 Phys. Rev. B 85 140520
[30]	Shimahara H 2000 Phys. Rev. B 61 R14936
[31]	Kuroki K, Arita R, Aoki H 2001 Phys. Rev. B 63 094509
[32]	Lebed A G 2012 Physica B 407 1803

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