Crystal structure and superconducting properties of Sc₅Ir₆Sn₁₈

Abstract

Sc5Ir6Sn18 crystallizes with a split variant of the Tb5Rh6Sn18 structure type (space group I41/acd, , ). DFT calculations confirmed the instability of the structural arrangement with the fully occupied and unsplit crystallographic sites. High quality single crystals were grown from a Sn melt. Sc5Ir6Sn18 is a diamagnetic metal showing a superconducting transition at a critical temperature K. The relatively low critical magnetic field 3.2 T as well as the obtained values of the specific heat ratio and energy-gap ratio suggest this system to be a weakly coupled BCS-like superconductor.

Crystal structure, chemical bonding, and electrical and thermal transport in Sc5Rh6Sn18

“…In the whole studied temperature range the same structural model, which is now characterized by reasonable thermal anisotropic displacements and stoichiometric 5:6:18 composition, was refined. The performed refinements confirm Sc 5 Rh 6 Sn 18 to crystallize with Sc 5 Ir 6 Sn 18 structure type 13 . In agreement with this finding, all reflections in the powder XRD patterns of Sc 5 Rh 6 Sn 18 were indexed with the same structural model.…”

“…As it is well known, non-centrosymmetric superconductors (SC) are preferable candidates for unconventional superconducting properties, which includes TRS breaking as well. 17 Taking all these observations into account as well as a strong structural disorder reported for isostructural Sc 5 Ir 6 Sn 18 superconductor 13 we performed an extensive study of the crystal structure of Sc 5 Rh 6 Sn 18 applying temperature dependent high-resolution powder and single crystal X-ray diffraction as well as transmission electron microscopy. To understand the obtained structural model the analysis of the chemical bonding situation assuming different structural models is performed.…”

“…B 12 ;B 13 ;B 23 ; 0.12(13);0.4(5);0.4(5) 0.06(12);0.5(14);-0.4(14); 0.06(14);0.6(14);-0.3(14); 0.1(2);0.3(27);0.0(25); 0.0(2);0.5(18);-0.5(17); Sc2 B 11 ;B 22 ;B 33 ; 0.33(3);0.37(3)0.56(3) 0.41(3);0.45(3);0.62(3); 0.50(4);0.55(4);0.67(4); 0.65(5);0.70(5);0.69(4); 0.64(5);0.71(5);0.83(5);; B 12 ;B 13 ;B 23 ; 0.00(3);0.02(3);0.01(3) -0.00(3);0.02(3);0.03(3); -0.02(3);0.03(3);0.02(3); -0.00(4);0.00(4);0.04(4); 0.02(4);0.03(4);0.03(4); Rh1 B 11 ;B 22 ;B 33 ; 0.28(2);0.25(2);0.51(2) 0.34(2);0.32(2);0.54(2); 0.43(2);0.41(2);0.59(2); 0.52(3);0.51(3);0.53(3); 0.49(3);0.47(3);0.68(3); B 12 ;B 13 ;B 23 ; -0.01(2);0;0 -0.02(2);0;0; -0.02(2);0;0; -0.02(2);0;0; -0.04(2);0;0; Rh2 B 11 ;B 22 ;B 33 ; 0.25(2);0.34(2);0.40(1); 0.32(1);0.41(2);0.43(1); 0.40(2);0.50(2);0.48(1); 0.49(2);0.59(2);0.45(2); 0.46(2);0.59(2);0.56(2); B 12 ;B 13 ;B 23 ;…”

Conventional isotropic s -wave superconductivity with strong electron-phonon coupling in Sc5Rh6Sn18

“…[24]. The performed diffraction studies showed Sc 5 Rh 6 Sn 18 [space group: I4 1 /acd, a = 13.5529(2) Å, c = 27.0976(7) Å] crystallizes with the Sc 5 Ir 6 Sn 18 type of structure [22]. The structural arrangement can be understood as a corner-sharing trigonal prism array with incorporated cuboctahedra, which are centered by Sc atoms, and 16-vertex polyhedra with the Sn1 atom in the center (Fig.…”

“…Tm 5 Rh 6 Sn 18 (T c = 2.2 K) is characterized by the coexistence of magnetism and reentrant superconductivity at zero magnetic field [20]. In contrast, conventional BCS superconductivity with an swave gap is observed for Sc 5 Ru 6 Sn 18 (T c = 3.5 K, B c2 = 2.6 T) [21] and Sc 5 Ir 6 Sn 18 (T c = 2.64 K, B c2 = 3.2 T) [22]. Interestingly, recent field-dependent low-temperature thermal conductivity measurements showed nodeless s-wave gaps for both Y 5 Rh 6 Sn 18 and Lu 5 Rh 6 Sn 18 [23].…”