On biholes in antiferromagnets-superconductors

In contrast to ferromagnets (FM), in the antiferromagnets (AF) the translation movement of holes in the low Hubbard zone and of electrons in the upper Hubbard zone is complicated. Thus, AF→FM transformation, accompanied by electric conductivity growth, occurs at the increase of current carrier density. However, in cuprate SC the superexchange AF-interaction is very intensive (Jij≅ 0.1 eV) and destruction of the nearest AF-arrangement is not profitable. It is demonstrated, that in AF the matrix element of bihole translation is essentially higher, than that of single hole. So, if the Coulomb repulsion is shielded sufficiently, formation of bihole with the nearest arrangement AF retention may turn to be energetically efficient. Then Bose-condensation of biholes must occur. The present experimental data are discussed