Effects of magnetic dopants in (Li0.8M0.2OH)FeSe (M = Fe, Mn, Co): Density functional theory study using a band unfolding technique

The effects of Fe dopants on the electronic bands structure of (Li0.8Fe0.2OH) FeSe are investigated by a band unfolding (k-projection) technique and first-principles supercell calculations. Doping 20% Fe into the LiOH layers causes electron donation to the FeSe layers, significantly changing the profile of bands around the Fermi level. Because of the weak bonding between the LiOH and FeSe layers the magnetic configuration of the dopants has onlyminor effects on the band structure. The electronic bands for the surface FeSe layer of (Li0.8Fe0.2OH) FeSe show noticeable differences compared to those of the inner layers, both in the location of the Fermi level and in details of the bands near the high symmetry points, resulting from different effective doping levels and the broken symmetry at the surface. The band structure for the surface FeSe layer with checkerboard antiferromagnetic order is reasonably consistent with angle-resolved photoemission results. The 3d transition metals Mn and Co have similar doping effects on the band structure of (LiOH) FeSe.