SrAuSi₃: A Noncentrosymmetric Superconductor

A novel strontium–gold silicide (SrAuSi 3 ) was successfully synthesized for the first time using a high-pressure technique, at ∼6 GPa. X-ray Rietveld analysis and scanning transmission electron microscopy studies clearly revealed that SrAuSi 3 crystallizes in a BaNiSn 3 -type structure, in space group I 4 mm with the following lattice parameters: a = 4.4090(1) Å, and c = 9.9475(3) Å. The structure was found not to have inversion symmetry in real space. From direct measurements of polycrystalline SrAuSi 3, the electrical resistivity was zero, the static magnetic susceptibility was almost a full volume Meissner diamagnetic signal, and the specific heat exhibited a sharp jump, all of which were accompanied by a phase transition due to bulk superconductivity at a critical temperature ( T C ) of 1.54 K. The SrAuSi 3 compound is the first noncentrosymmetric superconductor that includes Au as a principal constituent element.