Two types of magnetic polarons localized at impurities in an antiferromagnetic chain

摘要

The possibility of different types of magnetic polarons (ferrons) is discussed for an anti ferromagnetic (AF) chain doped by non-magnetic donor impurities. The conduction electrons are assumed to be bound by the impurities. It is shown that two types of ferrons can exist in such a system: ferrous with the sizes of the order of the localization length of the electron near the impurity, and those with more extended distortions of the AF order in the chain. The ferrons of the first type correspond to the ground state, whereas ferrons of the second type can be treated as metastable excitations. The energy of the excited states decreases with the growth in density of impurities. This is a signature of an attractive interaction between ferrons, which could provide a possible mechanism for a large-scale phase separation in manganites and related compounds. (c) 2005 Elsevier B.V. All rights reserved.