SrAuSi3: A Noncentrosymmetric Superconductor

A novel strontium-gold silicide (SrAuSi3) was successfully synthesized for the first time using a high-pressure technique, at similar to 6 GPa. X-ray Rietveld analysis and scanning transmission electron microscopy studies clearly revealed that SrAuSi3 crystallizes in a BaNiSn3-type structure, in space group I4mm with the following lattice parameters: a = 4.4090(1) angstrom, and c = 9.9475(3) angstrom. The structure was found not to have inversion symmetry in real space. From direct measurements of polycrystalline SrAuSi3, 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 SrAuSi3 compound is the first noncentrosymmetric superconductor that includes Au as a principal constituent element.