2004/06/21 by Yukitoshi Motome, Nobuo Furukawa, Naoto Nagaosa
Materials Science · Physics and Astronomy · #Chemical and Physical Properties of Materials #Magnetic and transport properties of perovskites and related materials #Multiferroics and related materials #cond-mat.str-el
paper · pdf · doi:10.1007/11417255_5
published as Lecture Notes in Physics 678, 71 (2005) · 16 pages, 7 figures, submitted to Wandlitz Days on Magnetism: Local-Moment Ferromagnets: Unique Properties for Modern Applications
arxiv created 2004/06/21 · openalex publication_date 2005/11/30 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/07/28
We theoretically explore the mechanism of the colossal magnetoresistance in manganese oxides by explicitly taking into account the phase competition between the double-exchange ferromagnetism and the charge-ordered insulator. We find that quenched disorder causes a drastic change of the multicritical phase diagram by destroying the charge-ordered state selectively. As a result, there appears a nontrivial phenomenon of the disorder-induced insulator-to-metal transition in the multicritical regime. On the contrary, the disorder induces a highly-insulating state above the transition temperature where charge-ordering fluctuations are much enhanced. The contrasting effects provide an understanding of the mechanism of the colossal magnetoresistance. The obtained scenario is discussed in comparison with other theoretical proposals such as the polaron theory, the Anderson localization, the multicritical-fluctuation scenario, and the percolation scenario.