Electronic structure of HgBa_2Ca_(n-1)Cu _nO_(2n)2 (n = 1, 2, 3) superconductor parent compounds from periodic hybrid density functional theory

摘要

The electronic structure of HgBa_2Ca_(n-1)Cu_nO_(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 12 magnetic centers at the Cu~(2+) sites. However, the presence of the HgO_2 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 CuO_2 planes in the unit cell, to the point that in the HgBa _2Ca_2Cu_3O_8 compound it becomes so small that one can claim that the resulting material is metallic. Nevertheless, the metallic character arises from the HgO_2 structural units and coexists with the antiferromagnetic order arising from the localized spins at the Cu2+ sites.