Multiband superconductivity in the topological Kramers nodal-line semimetals

Tian Shang; Jianzhou Zhao; Keqi Xia; Lun-Hui Hu; Yang Xu; Qingfeng Zhan; Dariusz Jakub Gawryluk; Toni Shiroka

doi:10.1103/k2t5-wcq1

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Multiband superconductivity in the topological Kramers nodal-line semimetals

Tian Shang, Jianzhou Zhao, Keqi Xia, Lun-Hui Hu, Yang Xu, Qingfeng Zhan, Dariusz Jakub Gawryluk, Toni Shiroka

DOI 10.1103/k2t5-wcq1 · Physical Review B

T1

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Abstract

Recent band-structure calculations predicted that the ruthenium-based ternary silicides are three-dimensional Kramers nodal-line semimetals. Among them, NbRuSi and TaRuSi show bulk superconductivity (SC) below Tc∼3K and 4 K, as well as spontaneous magnetic fields. The latter indicate the breaking of time-reversal symmetry and, thus, unconventional SC in both compounds. Previous temperature-dependent muon-spin spectroscopy studies failed to distinguish whether such compounds exhibit single-gap or multigap SC. Here we report on systematic measurements of the field-dependent muon-spin relaxation rates in the superconducting state and on temperature-dependent electrical resistivity and specific heat under applied magnetic fields. Both the upper critical field and the field-dependent superconducting relaxation are well described by a two-band model. By combining our experimental results with numerical band-structure calculations, we provide solid evidence for multiband SC in NbRuSi and TaRuSi, and thus offer further insight into the unconventional and topological nature of their superconductivity.

Source-reported materials — not catalogue approval

Formula	Reported Tc (K)	Pressure (GPa)	Type
NbRuSi Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	3	Pressure not reported	midpoint
NbRuSi Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	3.1	Pressure not reported	onset
TaRuSi Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	4.1	Pressure not reported	midpoint
TaRuSi Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	4	Pressure not reported	onset
NbReSi Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	—	Pressure not reported	unknown
HfRhGe Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	—	Pressure not reported	unknown
TaReSi Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	—	Pressure not reported	unknown