Unconventional sign-changing superconductivity near quantum criticality in YFe2Ge2

Abstract

I present the results of first principles calculations of the electronic structure and magnetic interactions for the recently discovered superconductor YFe2Ge2 and use them to identify the possible nature of superconductivity and quantum criticality in this compound. I find that the Fe 3d derived states near the Fermi level show a rich structure with the presence of both linearly dispersive and heavy bands. The Fermi surface exhibits nesting between hole and electron sheets that manifests as a peak in the susceptibility at (1/2,1/2). The antiferromagnetic spin fluctuations associated with this peak may be responsible for mediating the superconductivity in this compound resulting in a s± state similar to that of the previously discovered iron-based superconductors. I also find that various magnetic orderings are almost degenerate in energy, which indicates that the proximity to quantum criticality is due to competing magnetic interactions.

Source-reported materials — not catalogue approval

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