The electron pairing of K <sub> <i>x</i> </sub> Fe <sub> 2− <i>y</i> </sub> Se <sub>2</sub>
The electron pairing of K <sub> <i>x</i> </sub> Fe <sub> 2− <i>y</i> </sub> Se <sub>2</sub>
We studied the pairing instabilities in KxFe2−ySe2 using a two-stage functional renormalization group (FRG) method. Our results suggest the leading and subleading pairing symmetries are nodeless dx2−y2 and nodal extended s, respectively. In addition, despite having no Fermi surfaces we find the buried hole bands make important contributions to the …