Time reversal invariant single-gap superconductivity with upper critical field larger than the Pauli limit in

D Das, K Górnicka, Z Guguchia, J Jaroszynski… - Physical Review B, 2022 - APS
Physical Review B, 2022APS
Recently, compounds with noncentrosymmetric crystal structure have attracted much
attention for providing a rich playground in search for unconventional superconductivity. NbIr
2 B 2 is a new member to this class of materials harboring superconductivity below T c= 7.3
(2) K and a very high upper critical field that exceeds Pauli limit. Here we report on muon
spin rotation (μ SR) experiments probing the temperature and field dependence of effective
magnetic penetration depth in this compound. Our transverse-field-μ SR results suggest a …
Recently, compounds with noncentrosymmetric crystal structure have attracted much attention for providing a rich playground in search for unconventional superconductivity. is a new member to this class of materials harboring superconductivity below  K and a very high upper critical field that exceeds Pauli limit. Here we report on muon spin rotation () experiments probing the temperature and field dependence of effective magnetic penetration depth in this compound. Our transverse-field- results suggest a fully gapped -wave superconductivity. Furthermore, the estimated high value of the upper critical field is also supplemented by high-field transport measurements. Remarkably, the ratio obtained for () is comparable to those of unconventional superconductors. Zero-field data reveal no significant change in the muon spin relaxation rate above and below , evincing that time-reversal symmetry is preserved in the superconducting state. The presented results will stimulate theoretical investigations to obtain a microscopic understanding of the origin of superconductivity with preserved time-reversal symmetry in this unique noncentrosymmetric system.
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