Underdoped cuprate antiferromagnet as a two-dimensional antiferromagnetic metal

Abstract

An approach to describing the pseudogap state as a two-dimensional antiferromagnetic metal with non-Fermi charge carriers is developed for quasi-two-dimensional underdoped HTSC cuprates with one CuO2 plane. The model of local closed Varma currents is extended to holes of the ion Cu3+ surrounded by four ionic complexes Cu↑2+O42− (or Cu↓2+O42−). It is shown that taking account of the electron-vibrational interactions results in vibronic transitions from a nondegenerate state of the Cu3+ ion into doubly degenerate Cu↑2+ (or Cu↓2+) with splitting of the energy band for two types of quasilocal states of a “copper-oxygen” hole (vortex or antivortex), each of which moves in its own magnetic sublattice. The transfer of the vortex current from the “molecule” Cu3+O42− to the complex Cu↓2+O42− with the copper ion from the same magnetic sublattice creates the dynamical effect of a displacement of a Cu3+ ion to the site of a Cu↓2+ ion and a transition of the “molecule” Cu3+O42− into the complex Cu↓2+O42−.