Specific heat andμSR study on the noncentrosymmetric superconductor LaRhSi3

Abstract

We have investigated the superconducting properties of the noncentrosymmetric superconductor LaRhSi 3 by performing magnetization, specific heat, electrical resistivity and muon spin relaxation (µSR) measurements. LaRhSi 3 crystallizes with the BaNiSn 3 -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 T c = 2.16 ± 0.08 K. The low temperature specific heat data reveal that LaRhSi 3 is a weakly coupled bulk BCS superconductor and has an s-wave singlet ground state with an isotropic energy gap of ∼ 0.3 meV, 2∆ 0 /k B T c = 3.24. The specific heat data measured in applied magnetic field strongly indicate a type-I behaviour. 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 LaRhSi 3 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, H c0 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 H c0 = 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 LaRhSi 3 .

Type-I superconductivity in KBi2single crystals

“…The extracted electronic specific heat jump at T c (∆C es /γT c = 6.06) is much larger than the weakly coupled BCS value 1.43, indicating the strongly coupled superconductivity in KBi 2 . 24 The thermodynamic critical field H c (T ) can be obtained by integrating the differences of specific heats and the specific heats divided by temperature between the zero-field superconducting (s) and normal (n) states (H = 207 Oe) (free energy analysis), 8,25 …”

“…In contrast, type-I SCs are thought empirically to occur mainly in elementary metals and metalloids and type-I superconducting compounds are very rare. 2 Recently, however, serval binary and ternary compounds are found to be type-I SCs, for instance, YbSb 2 , 3,4 TaSi 2 , 5 LaPd 2 Ge 2 , 6 LaRh 2 Si 2 , 7 (Lu, Y, La)Pd 2 Si 2 , 7 LaRhSi 3 , 8 Ag 5 Pb 2 O 6 , 9 ScGa 3 and LuGa 3 . 10 These studies break the empirical relation between type-I superconductivity and elemental metals and enlarge the family of type-I SCs to binary and ternary compounds.…”

Probing the superconducting ground state of the noncentrosymmetric superconductorsCaTSi3(T= Ir, Pt) using muon-spin relaxation and rotation

“…Replacing Ce with a non-magnetic analogue such as La also produces superconductors which exhibit unusual properties. For example, LaRhSi 3 and LaPdSi 3 are type I superconductors, whereas LaPtSi 3 is type II 24,28 .…”

Muon spin relaxation and neutron scattering investigations of the noncentrosymmetric heavy-fermion antiferromagnet CeRhGe3

“…[6][7][8][9] Ce compounds of this series, CeTX 3 (X = Si and Ge), belong to the family of recently discovered noncentrosymmetric HFSC whose superconducting ground-state properties are dictated by an antisymmetric spin-orbit coupling (ASOC) as a consequence of the lack of inversion symmetry, along the [0 0 1] direction, in the tetragonal crystal structure. [10][11][12][13][14][15][16][17][18][19] This ASOC, in turn, results in the formation of a mixed pairing wave function with spin-singlet and spin-triplet components in the superconducting state.…”