Model of Renormalized Polarons for the Colossal Magnetoresistance Description

✍ Scribed by P. Młynarski; D. Baldomir; I. Gonzalez; L. Wojtczak

• Publisher: John Wiley and Sons
• Year: 2002
• Tongue: English
• Weight: 114 KB
• Volume: 233
• Category: Article
• ISSN: 0370-1972
• DOI: 10.1002/1521-3951(200209)233:1<170::aid-pssb170>3.0.co;2-z

✦ Synopsis

We consider ferromagnetic and electron-phonon interactions in doped manganite perovskites which constitute their magnetotransport properties. The present contribution follows the idea of Alexandrov and Bratkovsky that the conductivity has its polaronic character. In order to develop this idea we derive the effective number of the current density carriers in effect of the competition between the mobile and immobile polarons determined by the impurities. For this purpose, the Hamiltonian reflects the two sublattices structure, leading to two subbands which are both renormalized by the pseudoharmonic phonons in a way which allows us to consider dressed polarons depending on the mean square displacements of atoms from their equilibrium positions. The transition between these two subbands is of the insulator-metal phase transition nature and it is correlated with the ferromagnetic-paramagnetic transition. Finally, the derived effective number of mobile carriers is applied to calculations of the colossal magnetoresistance.