Preprints are manuscripts made publicly available before they have been submitted for formal peer review and publication. They might contain new research findings or data. Preprints can be a draft or final version of an author's research but must not have been accepted for publication at the time of submission.
posted on 04.04.2006by A.S. Alexandrov, A.M. Bratkovsky
A novel ferromagnetic transition, accompanied by carrier density collapse, is found in doped charge-transfer insulators with strong electron-phonon coupling.
The transition is driven by an exchange interaction of polaronic carriers with localized spins; the strength of the interaction determines whether the transition is first or second order. A giant drop in the number of current carriers during the transition, which is a consequence of bound pairs formation in the paramagnetic phase close to the transition, is extremely sensitive to an external magnetic field. This carrier density collapse describes the resistivity peak and the colossal magnetoresistance of doped manganites.
This is a pre-print. It is also available at: http://arxiv.org/abs/cond-mat/9806030. The definitive version: ALEXANDROV and BRATKOVSKY, 1999. Carrier density collapse and colossal magnetoresistance in doped manganites. Physical Review Letters, 82(1),pp. 141-144, is available at: http://prl.aps.org/.