Specific heat and μSR study on the noncentrosymmetric superconductor LaRhSi3

Abstract

We have investigated the superconducting properties of the noncentrosymmetric superconductor LaRhSi3 by performing magnetization, specific heat, electrical resistivity, and muon spin relaxation (μSR) measurements. LaRhSi3 crystallizes with the BaNiSn3-type tetragonal structure (space group I4 mm), as confirmed through our neutron diffraction study. Magnetic susceptibility, electrical resistivity and specific heat data reveal a sharp and well-defined superconducting transition at Tc=2.16±0.08 K. The low-temperature specific heat data reveal that LaRhSi3 is a weakly coupled bulk BCS superconductor and has an s-wave singlet ground state with an isotropic energy gap of ~0.3 meV, 2Δ0/kBTc=3.24. The specific heat data measured in an applied magnetic field strongly indicate a type I behavior. Type I superconductivity in this compound is also inferred from the Ginzburg-Landau parameter, κ=0.25. Various superconducting parameters, including the electron-phonon coupling strength, penetration depth, and coherence length, characterize LaRhSi3 as a moderate dirty-limit superconductor. A detailed study of the magnetic field-temperature (H−T) phase diagram is presented and from a consideration of the free energy, the thermodynamic critical field, Hc0, is estimated to be 17.1±0.1 mT, which is in very good agreement with that estimated from the transverse field μSR measurement that gives Hc0=17.2±0.1 mT. The transverse field μSR results are consistent with conventional type I superconductivity in this compound. Further, the zero field μSR results indicate that time-reversal symmetry is preserved when entering the superconducting state, also supporting a singlet pairing superconducting ground state in LaRhSi3.

Source-reported materials — not catalogue approval

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