Possible unconventional pairing in $(\text{Ca,Sr}{)}_3(\text{Ir,Rh}{)}_4{\text{Sn}}_{13}$ superconductors revealed by controlling disorder

Abstract

We study the evolution of temperature-dependent resistivity with controlled point-like disorder induced by 2.5 MeV electron irradiation in stoichiometric compositions of the "3-4-13" stannides, $(\text{Ca,Sr}{)}_3(\text{Ir,Rh}{)}_4{\text{Sn}}_{13}$.Three of these cubic compounds exhibit a microscopic coexistence of charge-density wave (CDW) order and superconductivity (SC), while ${\text{Ca}}_3{\text{Rh}}_4{\text{Sn}}_{13}$ does not develop CDW order. As expected, the CDW transition temperature, $T_{\text{CDW}}$, is universally suppressed by irradiation in all three compositions. The superconducting transition temperature, $T_c$, behaves in a more complex manner. In ${\text{Sr}}_3{\text{Rh}}_4{\text{Sn}}_{13}$, it increases initially in a way consistent with a direct competition of CDW and SC, but quickly saturates at higher irradiation doses. In the other three compounds, $T_c$ is monotonically suppressed by irradiation. The strongest suppression is found in ${\text{Ca}}_3{\text{Rh}}_4{\text{Sn}}_{13}$, which does not have CDW order. We further examine this composition by measuring the London penetration depth, $\lambda (T)$, from which we derive the superfluid density. The result unambiguously points to a weak-coupling, full single gap, isotropic superconducting state. Therefore, we must explain two seemingly incompatible experimental observations: a single isotropic superconducting gap and a significant suppression of $T_c$ by non-magnetic disorder. We conduct a quantitative theoretical analysis based on a generalized Anderson theorem which points to an unconventional multiband $s^{+-}$-pairing state where the sign of the order parameter is different on one (or a small subset) of the smaller Fermi surface sheets, but remains overall fully-gapped.

References in corpus (18)

• High-temperature superconductivity in iron-based materials
• Magnetic Penetration Depth in Unconventional Superconductors
• A Sharp Peak of the Zero-Temperature Penetration Depth at Optimal Composition in BaFe2(As1-xPx)2
• Pressure induced superconductivity on the border of magnetic order in MnP
• Anisotropy of the Optimally-Doped Iron Pnictide Superconductor Ba(Fe0.926Co0.074)2As2
• Superfluid density and specific heat within self-consistent scheme for two-band superconductor
• Exotic Superconducting States in FeSe-based Materials
• Penetration depth study of superconducting gap structure of 2\textit{H}-NbSe${}_2$
• Disorder-induced topological change of the superconducting gap structure in iron pnictides
• Ambient Pressure Structural Quantum Critical Point in the Phase Diagram of (Ca${}_x$Sr${}_{1-x}$)${}_3$Rh${}_4$Sn${}_{13}$
• Crystal structure and phonon softening in Ca3Ir4Sn13
• Unconventional charge-density wave in Sr3Ir4Sn13 cubic superconductor revealed by optical spectroscopy study
• Superconducting and magnetic properties of Sr3Ir4Sn13
• Impact of Disorder on the Superconducting Phase Diagram in BaFe${}_2$(As${}_{1-x}$P${}_x$)${}_2$
• Meissner-London susceptibility of superconducting right circular cylinders in an axial magnetic field
• Pair breaking due to orbital magnetism in iron-based superconductors
• Multi-band $s_{++}$ superconductivity in ${\text{V}}_3\text{Si}$ determined from the response to a controlled disorder
• London penetration depth measurements using tunnel diode resonators

Cited by in corpus (6)

• Peak in the critical current density in (Ca${}_x$Sr${}_{1-x}$)${}_3$Rh${}_4$Sn${}_{13}$ tuned towards the structural quantum critical point
• Time-reversal-symmetry Breaking in the Superconducting State of ScS
• Time-reversal symmetry breaking in superconducting low-carrier-density quasi-skutterudite Lu3Os4Ge13
• Enhancement of the Curie temperature in single crystalline ferromagnetic LaCrGe${}_3$ by electron irradiation-induced disorder
• Robust superconductivity and the suppression of charge-density wave in ${\text{Ca}}_3({\text{Ir}}_{1-x}{\text{Rh}}_x{)}_4{\text{Sn}}_{13}$ single crystals at ambient pressure
• Reaching Quantum Critical Point by Adding Non-magnetic Disorder in Single Crystals of Superconductor $({\text{Ca}}_x{\text{Sr}}_{1-x}{)}_3{\text{Rh}}_4{\text{Sn}}_{13}$