New type of antiferromagnetic polaron and bipolaron in high-Tc superconductors

Abstract The possibility of formation of a new type of polaron based on the quantum aniferromagnet (AF) model is reported. We take into account exchange interactions between localized d–d spins of the AF, as well as the p–d interaction of the AF with p-carriers. The energy minimum is found when maximum charge density occurs on every second spin. The formation of such “comb-like” polarons results from the damping of quantum fluctuations and the appearance of Van Vleck-like staggered magnetization. Such polarons tend to form pairs coupled by an AF “glue”.