中国物理B ›› 2025, Vol. 34 ›› Issue (11): 117104-117104.doi: 10.1088/1674-1056/ae001a

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Unconventional superconductivity in Cr-based nitride La3Cr10-xN11

M Y Zou(邹牧远)1, J C Jiao(焦嘉琛)1, K W Chen(陈锴文)1, C Y Jiang(姜程予)1, C S Chen(陈长胜)1, X Li(李鑫)1, Q Wu(吴琼)1, N Y Zhang(张宁远)1, O O Bernal2, P C Ho3, A Koda4,5, D E MacLaughlin6, and L Shu(殳蕾)1,7,†   

  1. 1 State Key Laboratory of Surface Physics, Department of Physics, Fudan University, Shanghai 200433, China;
    2 Department of Physics and Astronomy, California State University, Los Angeles, California 90032, USA;
    3 Department of Physics, California State University, Fresno, California 93740, USA;
    4 Muon Science Laboratory and Condensed Matter Research Center, Institute of Materials Structure Science, High Energy Accelerator Research Organization (KEK), Tsukuba, Ibaraki 305-0801, Japan;
    5 Department of Materials Structure Science, The Graduate University for Advanced Studies (Sokendai), Tsukuba, Ibaraki 305-0801, Japan;
    6 Department of Physics and Astronomy, University of California, Riverside, California 92521, USA;
    7 Shanghai Research Center for Quantum Sciences, Shanghai 201315, China
  • 收稿日期:2025-07-05 修回日期:2025-08-10 接受日期:2025-08-28 发布日期:2025-10-30
  • 基金资助:
    We are grateful to G. D. Morris, B. Hitti, and D. Arsenau of the TRIUMF CMMS and the staff of J-PARC S1 (Experiment No. 2024A0208) for their valuable help during the SR experiments. This work was funded by the National Key Research and Development Program of China (Grant No. 2022YFA1402203), the National Natural Science Foundations of China (Grant No. 12174065), the Innovation Program for Quantum Science and Technology (Grant No. 2024ZD0300104), and the Shanghai Municipal Science and Technology Major Project (Grant No. 2019SHZDZX01).

Unconventional superconductivity in Cr-based nitride La3Cr10-xN11

M Y Zou(邹牧远)1, J C Jiao(焦嘉琛)1, K W Chen(陈锴文)1, C Y Jiang(姜程予)1, C S Chen(陈长胜)1, X Li(李鑫)1, Q Wu(吴琼)1, N Y Zhang(张宁远)1, O O Bernal2, P C Ho3, A Koda4,5, D E MacLaughlin6, and L Shu(殳蕾)1,7,†   

  1. 1 State Key Laboratory of Surface Physics, Department of Physics, Fudan University, Shanghai 200433, China;
    2 Department of Physics and Astronomy, California State University, Los Angeles, California 90032, USA;
    3 Department of Physics, California State University, Fresno, California 93740, USA;
    4 Muon Science Laboratory and Condensed Matter Research Center, Institute of Materials Structure Science, High Energy Accelerator Research Organization (KEK), Tsukuba, Ibaraki 305-0801, Japan;
    5 Department of Materials Structure Science, The Graduate University for Advanced Studies (Sokendai), Tsukuba, Ibaraki 305-0801, Japan;
    6 Department of Physics and Astronomy, University of California, Riverside, California 92521, USA;
    7 Shanghai Research Center for Quantum Sciences, Shanghai 201315, China
  • Received:2025-07-05 Revised:2025-08-10 Accepted:2025-08-28 Published:2025-10-30
  • Contact: L Shu E-mail:Leishu@fudan.edu.cn
  • Supported by:
    We are grateful to G. D. Morris, B. Hitti, and D. Arsenau of the TRIUMF CMMS and the staff of J-PARC S1 (Experiment No. 2024A0208) for their valuable help during the SR experiments. This work was funded by the National Key Research and Development Program of China (Grant No. 2022YFA1402203), the National Natural Science Foundations of China (Grant No. 12174065), the Innovation Program for Quantum Science and Technology (Grant No. 2024ZD0300104), and the Shanghai Municipal Science and Technology Major Project (Grant No. 2019SHZDZX01).

摘要: Magnetization, specific heat, and muon spin relaxation (μSR) experiments have been carried out on the Cr-based nitride superconductor La$_3$Cr$_{10-x}$N$_{11}$, which exhibits a number of unconventional superconducting properties. The susceptibility $\chi(T)$ shows nearly perfect superconducting diamagnetism ($4\pi\chi(T=0) \approx -1$) and a remarkably high upper critical field $\mu_0H_{\rm c2} = 11.2$~T. The specific heat displays activated exponential behavior $\exp(-\varDelta_0/k_{\rm B}T)$, together with a large and field-dependent residual Sommerfeld coefficient. Transverse-field muon spin relaxation (μSR) measurements suggest s+s-wave or p-wave pairing symmetry, ruling out single s-wave pairing. Zero-field μSR yields no statistically significant evidence for time reversal symmetry breaking (TRSB), and places an upper bound of 1.5(1.3)~ms$^{-1}$ on any TRSB-induced muon relaxation rate at $T = 0$. Our results suggest that the unconventional superconductivity in $Ln_3\rm Cr_{10-x}N_{11}$, $Ln ={\rm La}$ and Pr, is mainly due to Cr 3d electrons and is similar in both compounds, whereas Pr 4f electrons are primarily responsible for the TRSB superconductivity observed in Pr$_3$Cr$_{10-x}$N$_{11}$.

关键词: muon spin relaxation/rotation, heavy fermion superconductor, chromium-based superconductor

Abstract: Magnetization, specific heat, and muon spin relaxation (μSR) experiments have been carried out on the Cr-based nitride superconductor La$_3$Cr$_{10-x}$N$_{11}$, which exhibits a number of unconventional superconducting properties. The susceptibility $\chi(T)$ shows nearly perfect superconducting diamagnetism ($4\pi\chi(T=0) \approx -1$) and a remarkably high upper critical field $\mu_0H_{\rm c2} = 11.2$~T. The specific heat displays activated exponential behavior $\exp(-\varDelta_0/k_{\rm B}T)$, together with a large and field-dependent residual Sommerfeld coefficient. Transverse-field muon spin relaxation (μSR) measurements suggest s+s-wave or p-wave pairing symmetry, ruling out single s-wave pairing. Zero-field μSR yields no statistically significant evidence for time reversal symmetry breaking (TRSB), and places an upper bound of 1.5(1.3)~ms$^{-1}$ on any TRSB-induced muon relaxation rate at $T = 0$. Our results suggest that the unconventional superconductivity in $Ln_3\rm Cr_{10-x}N_{11}$, $Ln ={\rm La}$ and Pr, is mainly due to Cr 3d electrons and is similar in both compounds, whereas Pr 4f electrons are primarily responsible for the TRSB superconductivity observed in Pr$_3$Cr$_{10-x}$N$_{11}$.

Key words: muon spin relaxation/rotation, heavy fermion superconductor, chromium-based superconductor

中图分类号:  (Strongly correlated electron systems; heavy fermions)

  • 71.27.+a
74.70.Tx (Heavy-fermion superconductors) 76.75.+i (Muon spin rotation and relaxation)