Conventional $s$-wave Superconductivity in LaRh${}_2$As${}_2$; the Analog without the 4$f$ Electrons of CeRh${}_2$As${}_2$

Abstract

Superconductor LaRh${}_2$As${}_2$ has the same crystal structures as CeRh${}_2$As${}_2$, which exhibits superconducting (SC) multiphase in the $c$-axis magnetic field. Although the SC transition temperatures $T_c$ are similar, around 0.3 K, LaRh${}_2$As${}_2$ shows conventional type-II superconductivity with a small upper critical field $H_{c2}\sim$ 10 mT. At present, the SC properties of LaRh${}_2$As${}_2$ have not been clarified yet. We performed ${}^{75}$As-nuclear quadrupole resonance (NQR) measurements on LaRh${}_2$As${}_2$ to investigate the SC properties and gap structure. $1/T_1$ shows a clear coherence peak just below $T_c$ and an exponential decrease at lower temperatures, suggesting full-gap $s$-wave superconductivity. The numerical calculations based on an $s$-wave SC model reveal an SC gap size of $\Delta (0)/k_B{T}_c\sim 1.48$, consistent with the weak-coupling $s$-wave superconductivity. These results suggest that the 4$f$ electrons in CeRh${}_2$As${}_2$ not only enhance the orbital limiting field but also contribute to the formation of unconventional superconductivity with SC multiphase.

References in corpus (13)

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• Possible quadrupole density wave in the superconducting Kondo lattice CeRh2As2
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• Anisotropic magnetic and quadrupolar H-T phase diagram of CeRh2As2
• Appearance of $c$-axis magnetic moment in odd-parity antiferromagnetic state in CeRh${}_2$As${}_2$ revealed by ${}^{75}$As-NMR
• The phase diagram of CeRh${}_2$As${}_2$ for out-of-plane magnetic field

Cited by in corpus (2)

• Unveiling the superconducting scenario in multiphase superconductor CeRh${}_2$As${}_2$ from space-group symmetry analysis and DFT calculations
• Multipolar fluctuations from localized 4f electrons in CeRh2As2