Superconductivity and Magnetism in YFe$_2$Ge$_2$

Abstract

We report calculations of the electronic structure and magnetic properties of YFe$_2$Ge$_2$ and discuss the results in terms of the observed superconductivity near magnetism. We find that YFe$_2$Ge$_2$ is a material near a magnetic quantum critical point based on comparison of standard density functional results that predict magnetism with experiment. The band structure and Fermi surfaces are very three dimensional and higher conductivity is predicted in the $c$-axis direction. The magnetism is of Stoner type and is predominately from an in-plane ferromagnetic tendency. The inter-layer coupling is weak giving a perhaps 2D character to the magnetism, which is in contrast to the conductivity and may be important for suppressing the ordering tendency. This is compatible with a triplet superconducting state mediated by spin fluctuations.