Fermi Liquid Description of X-ray Absorption Spectra in Overdoped LSCO

We show that a paramagnetic self-energy correction [1] to the real-space Greens function code FEFF9 [2] can provide a good description of the x-ray absorption spectra (XAS) of cuprate system such as $La_{2-x}Sr_xCuO_4$ (LSCO). This self-energy includes coupling to the both charge and magnetic excitations. We also find good agreement with recent XAS results of Peets $et al$ [3] in the over-doped regime of LSCO. We have also investigated various prescriptions for including core-hole effects. We infer that at low-doping, the system behaves as an anti-ferromagnetic insulator, while Fermi liquid physics is recovered at high doping. [1] Tanmoy Das, R.S. Markiewicz, and A. Bansil, Phys.Rev. B {\bf {77}}, 134516 (2008). [2] J.J. Rehr $et al.$, Comptes Rendus Physique {\bf {10}}, 548 (2009). [3] D.C. Peets $et al.$,Phys. Rev. Lett {\bf {103}}, 087402 (2009).