Electronic structure of SrPd2Ge2 single crystals is studied by angle-resolved photoemission spectroscopy (ARPES), scanning tunneling spectroscopy (STS) and band-structure calculations within the local-density approximation (LDA). The STS measurements show single s-wave superconducting energy gap \Delta(0) = 0.5 meV. Photon-energy dependence of the observed Fermi surface reveals a strongly three-dimensional character of the corresponding electronic bands. By comparing the experimentally measured and calculated Fermi velocities a renormalization factor of 0.95 is obtained, which is much smaller than typical values reported in Fe-based superconductors. We ascribe such an unusually low band renormalization to the different orbital character of the conduction electrons and using ARPES and STS data argue that SrPd2Ge2 is likely to be a conventional superconductor, which makes it clearly distinct from isostructural iron pnictide superconductors of the "122" family.
@article{arxiv.1106.4585,
title = {Evidence for conventional superconductivity in SrPd2Ge2},
author = {T. K. Kim and A. N. Yaresko and V. B. Zabolotnyy and A. A. Kordyuk and D. V. Evtushinsky and N. H. Sung and B. K. Cho and T. Samuely and P. Szabó and J. G. Rodrigo and J. T. Park and D. S. Inosov and P. Samuely and B. Büchner and S. V. Borisenko},
journal= {arXiv preprint arXiv:1106.4585},
year = {2012}
}