We report heavy electron behavior in unconventional superconductor YFe2Ge2 (TC=1.2 K). We directly observe very heavy bands (meff∼25me) within ∼10 meV of the Fermi level EF using angle-resolved photoelectron spectroscopy (ARPES). The flat bands reside at the X points of the Brillouin zone and are composed principally of dxz and dyz orbitals. We utilize many-body perturbative theory, GW, to calculate the electronic structure of this material, obtaining excellent agreement with the ARPES data with relatively minor band renormalizations and band shifting required. We obtain further agreement at the Dynamical Mean Field Theory (DMFT) level, highlighting the emergence of the many-body physics at low energies (near EF) and temperatures.
@article{arxiv.2311.09492,
title = {Flat Bands at the Fermi Level in Unconventional Superconductor YFe2Ge2},
author = {R. Kurleto and C. -H. Wu and S. Acharya and D. M. Narayan and B. S. Berggren and P. Hao and A. Shackelford and H. R. Whitelock and Z. Sierzega and M. Hashimoto and D. Lu and C. Jozwiak and R. P. Cline and D. Pashov and J. Chen and M. van Schilfgaarde and F. M. Grosche and D. S. Dessau},
journal= {arXiv preprint arXiv:2311.09492},
year = {2023}
}