Contrast to superconducting compounds SrNi2Ge2 (Tc = 1.1 K) and SrPd2Ge2 (Tc= 3.2 K) with the BaFe2-As2-type body-center-tetragonal (122-bct) layer structure (space group I4/mmm), SrPt2Ge2 crystallized in a pseudo-tetragonal, monoclinic structure with space group P21 and lattice parameters a = 0.4401(4) nm< b = 0.4435(4) nm, c = 0.9764(10) nm and β = 90.5° >90°. Superconductivity with Tc=10.2K was observed in this new compound. However, a weak diamagnetic shielding signal of -3.2 × 10 2 cm3/mol at 2K indicates that superconductivity is not from the bulk monoclinic phase but from a minor metastable 122-bct high-temperature phase with a ∼ 0.44 nm, c ∼ 0.98 nm, β = 90°. This is the highest Tc reported outside the iron-based layer compounds with the 122-bct structure. High-Tc superconductivity is due to strong quasi-2D Pt-Ge-Pt 5d xz, yz-4p-5dxz, yz hybridization in the Pt-Ge layer with squeezed PtGe4 tetrahedral crystal field and Pt-5d8 spin-orbital interaction in the metastable 122-bct phase and is another example of multi-band (dxz/dyz/dxy) non-conventional s-wave superconductor.
- 122-bct layer crystal structure
- New superconductors
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics
- Energy Engineering and Power Technology
- Electrical and Electronic Engineering