Signature of Local Structure Anomaly at Tc in the Nb3Ge Superconductor

We report local structure of Nb3Ge intermetallic superconductor by Ge K-edge extended X-ray absorption fine structure (EXAFS) measurements performed in the temperature range of 6-300 K, with an emphasis to determine the local and instantaneous atomic displacements across the superconducting transition temperature T-c. We find that the temperature dependent correlated Debye-Waller factor of the Ge-Nb bonds shows a drop at the T-c while cooling the sample, similar to the one observed in the high-T-c cuprate superconductors. The results provide a clear indication of an intimacy between the local atomic displacements and the short coherence superconductivity, and suggests that local electron-lattice interaction should be considered to explain the high-T-c superconductivity in these materials.