%0 Journal Article
%T Orbital Symmetry and Orbital Excitations in High-Tc Superconductors
%J Condensed Matter | An Open Access Journal from MDPI
%D 2019
%R https://doi.org/10.3390/condmat4020046
%X We discuss a few possibilities of high- T c superconductivity with more than one orbital symmetry contributing to the pairing. First, we show that the high energies of orbital excitations in various cuprates suggest a simplified model with a single orbital of x 2 £¿ y 2 symmetry doped by holes. Next, several routes towards involving both e g orbital symmetries for doped holes are discussed: (i) some give superconductivity in a CuO 2 monolayer on Bi2212 superconductors, Sr 2 CuO 4 £¿ ¦Ä , Ba 2 CuO 4 £¿ ¦Ä , while (ii) others as nickelate heterostructures or Eu 2 £¿ x Sr x NiO 4 , could in principle realize it as well. At low electron filling of Ru ions, spin-orbital entangled states of t 2 g symmetry contribute in Sr 2 RuO 4 . Finally, electrons with both t 2 g and e g orbital symmetries contribute to the superconducting properties and nematicity of Fe-based superconductors, pnictides or FeSe. Some of them provide examples of orbital-selective Cooper pairing. View Full-Tex
%U https://www.mdpi.com/2410-3896/4/2/46