NbOsSi and TaOsSi – Two new superconducting ternary osmium silicides

Crystal structure and superconductivity of new ternary MTGe germanides (M = Ti, Zr, Hf and T = Ru, Os, Rh, Ir)

Elastic, electronic, thermodynamic and transport properties of XOsSi (X=Nb, Ta) superconductors: First-principles calculations

Crystalline symmetry is a defining factor of the electronic band topology in solids, where many-body interactions often induce a spontaneous breaking of symmetry. Superconductors lacking an inversion center are among the best systems to study such effects or even to achieve topological superconductivity. Here, we demonstrate that TRuSi materials (with T a transition metal) belong to this class. Their bulk normal states behave as three-dimensional Kramers nodal-line semimetals, characterized by large antisymmetric spin-orbit couplings and by hourglass-like dispersions. Our muon-spin spectroscopy measurements show that certain TRuSi compounds spontaneously break the time-reversal symmetry at the superconducting transition, while unexpectedly showing a fully gapped superconductivity. Their unconventional behavior is consistent with a unitary (s + ip) pairing, reflecting a mixture of spin singlets and spin triplets. By combining an intrinsic time-reversal symmetry-breaking superconductivity with nontrivial electronic bands, TRuSi compounds provide an ideal platform for investigating the rich interplay between unconventional superconductivity and the exotic properties of Kramers nodal-line/hourglass fermions.

https://www.science.org/doi/pdf/10.1126/sciadv.abq6589?download=true

Unconventional superconductivity in topological Kramers nodal-line semimetals

We report the synthesis, crystal structure, superconductivity and physical property characterizations of the ternary equiatomic compound ScRuSi. Polycrystalline samples of ScRuSi were prepared by an arc-melting method. The as-prepared samples were identified as the orthorhombic Co2P-type o-ScRuSi by powder x-ray diffraction analysis. Electrical resistivity measurements show o-ScRuSi to be a metal which superconducts below a T c of 3.1 K; the upper critical field μ 0 H c2(0) is estimated to be 0.87 T. The magnetization and specific heat measurements confirm the bulk type-II superconductivity in o-ScRuSi, with a specific heat jump within the BCS weak coupling limit. o-ScRuSi is the first Co2P-type superconductor to contain scandium. After annealing at 1273 K for a week, o-ScRuSi transforms into hexagonal Fe2P-type h-ScRuSi, which is a Pauli-paramagnetic metal with no superconductivity observed above 1.8 K.

https://iopscience.iop.org/article/10.1088/1361-6668/30/2/025008/pdf

Superconductivity at 3.1 K in the orthorhombic ternary silicide ScRuSi

Relationships between occurrence of superconductivity and crystal structure in new equiatomic ternary silicides MTSi (M = Ti, Zr, Hf and T = Ru, Os, Rh)

Wang Xian Zhong

Papers

Relationships between occurrence of superconductivity and crystal structure in new equiatomic ternary silicides MTSi (M = Ti, Zr, Hf and T = Ru, Os, Rh)