Muon spin relaxation study of the layered kagome superconductor <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msub><mml:mi>CsV</mml:mi><mml:mn>3</mml:mn></mml:msub><mml:msub><mml:mi>Sb</mml:mi><mml:mn>5</mml:mn></mml:msub></mml:mrow></mml:math>
Zhaoyang Shan, Pabitra Kumar Biswas⃰, S. K. Ghosh, Tymoteusz Tula, A. D. Hillier, D. T. Adroja, Stephen P. Cottrell, Guang‐Han Cao, Yi Liu, Xiaofeng Xu, Yu Song, Huiqiu Yuan, M. Smidman
Abstract
The ${\mathbb{Z}}_{2}$ topological metals $R{\mathrm{V}}_{3}{\mathrm{Sb}}_{5}$ ($R$ = K, Rb, Cs) with a layered kagome structure provide a unique opportunity to investigate the interplay between charge order, superconductivity, and topology. Here, we report muon-spin relaxation/rotation ($\ensuremath{\mu}\mathrm{SR}$) measurements performed on $\mathrm{Cs}{\mathrm{V}}_{3}{\mathrm{Sb}}_{5}$ across a broad temperature range, in order to uncover the nature of the charge density wave order and superconductivity in this material. From zero-field $\ensuremath{\mu}\mathrm{SR}$, we find that spontaneous magnetic fields appear below 50 K, which is well below the charge density wave transition (${T}^{*}\ensuremath{\sim}93$ K). We show that these spontaneous fields are dynamic in nature making it difficult to associate them with a hidden static order. The superconducting state of $\mathrm{Cs}{\mathrm{V}}_{3}{\mathrm{Sb}}_{5}$ is found to preserve time-reversal symmetry, and the transverse-field $\ensuremath{\mu}\mathrm{SR}$ results are consistent with a superconducting state that has two fully open gaps.