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

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

We have investigated the ternary noncentrosymmetric superconductors TaXSi (X=Re, Ru) by magnetization, resistivity, and specific heat measurements. The samples crystallize in orthorhombic TiFeSi structure having superconducting transition Tc = 5.32 K and 3.91 K, for TaReSi and TaRuSi respectively. Specific heat measurements indicated an s-wave nature of both materials with a moderately coupled nature. However, a low value of specific heat jump and the concave nature of the upper critical field suggests a nontrivial superconducting gap.

Superconducting properties of the non-centrosymmetric Superconductors TaXSi (X= Re, Ru)

Ternary noncentrosymmetric superconductors TaXSi (X = Re, Ru) investigated by magnetization, resistivity, and specific heat measurements. It crystallize in the orthorhombic TiFeSi-type structure with superconducting transition Tc = 5.32 K and 3.91 K for TaReSi and TaRuSi, respectively. A low value of specific heat jump and the upper critical field concave nature suggests a nontrivial superconducting gap.

Superconducting properties of the non-centrosymmetric superconductors TaXSi (X = Re, Ru)

The structural, mechanical and electronic properties of NbXSi (X=Fe, Co, Ni, Ru, Rh, Pd, Os, Ir and Pt) compounds from first-principles calculations

A series of ternary equiatiomic transition metal silicidesMM′Si (M=Zr, Nb, Ta;M′=Ru, Re) and Zr1/2
 M
 1/2 RuSi (M=Nb, Ta) have been synthesized and characterized. Guinier x-ray data clearly indicate that the compoundsMM′Si (M=Nb, Ta;M′=Ru, Re) crystallize with the orthorhombic TiFeSi-structure. This is contrary to one of the literature reports ascribing the hexagonal ZrRuSi structure toMReSi,M=Nb, Ta. ZrRuSi and Zr1/2
 M
 1/2RuSi (M=Nb, Ta), however, crystallize with the ZrRuSi structure. All the compounds are metallic and exhibit small and negative Seebeck coefficients. Superconductivity has been discovered inMM′Si,M=Nb, Ta;M′=Ru, Re and the transition temperatures, as measured by the low frequency a.c. susceptibility technique, range from 2·7 to 5·1 K. Zr1/2Nb1/2RuSi is not superconducting above 2·2 K. The observed properties are explained in terms of the electronic charge transfer effects and crystal structures adopted by these metal excess ternary silicides.

W Paulus

Papers

Structure and superconductivity studies on ternary equiatomic silicides,MM′Si