Electronic structure of HgBa2Can-1CunO2n+2 (n=1, 2, 3) superconductor parent compounds from periodic hybrid density functional theory

The electronic structure of HgBa(2)Ca(n-1)CunO(2n+2) (n = 1, 2, and 3) high T-c superconductor parent compounds has been investigated by means of periodic hybrid density functional theory. Similar to other cuprates, these materials are predicted to exhibit an antiferromagnetic ground state with well localized S = 1/2 magnetic centers at the Cu2+ sites. However, the presence of the HgO2 structural units largely defines the nature of states dominating the energy range around Fermi energy. This results in a complex charge transfer character of the insulating gap which decreases when increasing the number of CuO2 planes in the unit cell, to the point that in the HgBa2Ca2Cu3O8 compound it becomes so small that one can claim that the resulting material is metallic. Nevertheless, the metallic character arises from the HgO2 structural units and coexists with the antiferromagnetic order arising from the localized spins at the Cu2+ sites. (C) 2011 American Institute of Physics. [doi:10.1063/1.3553259]