Local spectroscopic evidence for a nodeless magnetic kagome superconductor CeRu<sub>2</sub>
C. Mielke, H. Liu, Debarchan Das, J-X Yin, Liangzi Deng, Jonathan Spring, Ritu Gupta, M. Medarde, C. W. Chu, R. Khasanov, Z M Hasan, Youguo Shi, H. Luetkens, Zurab Guguchia
Abstract
Abstract We report muon spin rotation ( µ SR) experiments on the microscopic properties of superconductivity and magnetism in the kagome superconductor CeRu 2 with <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msub> <mml:mi>T</mml:mi> <mml:mrow> <mml:mrow> <mml:mi mathvariant="normal">c</mml:mi> </mml:mrow> </mml:mrow> </mml:msub> <mml:mo>≃</mml:mo> <mml:mn>5</mml:mn> </mml:math> K. From the measurements of the temperature-dependent magnetic penetration depth λ , the superconducting order parameter exhibits nodeless pairing, which fits best to an anisotropic s -wave gap symmetry. We further show that the <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msub> <mml:mi>T</mml:mi> <mml:mrow> <mml:mrow> <mml:mi mathvariant="normal">c</mml:mi> </mml:mrow> </mml:mrow> </mml:msub> </mml:math> / λ −2 ratio is comparable to that of unconventional superconductors. Furthermore, the powerful combination of zero-field (ZF)- µ SR and high-field µ SR has been used to uncover magnetic responses across three characteristic temperatures, identified as <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msubsup> <mml:mi>T</mml:mi> <mml:mn>1</mml:mn> <mml:mrow> <mml:mo>∗</mml:mo> </mml:mrow> </mml:msubsup> <mml:mo>≃</mml:mo> <mml:mn>110</mml:mn> </mml:math> K, <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msubsup> <mml:mi>T</mml:mi> <mml:mn>2</mml:mn> <mml:mrow> <mml:mo>∗</mml:mo> </mml:mrow> </mml:msubsup> <mml:mo>≃</mml:mo> <mml:mn>65</mml:mn> </mml:math> K, and <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msubsup> <mml:mi>T</mml:mi> <mml:mn>3</mml:mn> <mml:mrow> <mml:mo>∗</mml:mo> </mml:mrow> </mml:msubsup> <mml:mo>≃</mml:mo> <mml:mn>40</mml:mn> </mml:math> K. Our experiments classify CeRu 2 as an exceedingly rare nodeless magnetic kagome superconductor.