Naive model from 1970th applied to CMR manganites: it seems to work

Abstract

Existing experimental data for various colossal magnetoresistance manganites have been examined employing an ovesimplified model that roots in 1970th. This model considers a classical semiconductor where conducting bands are affected by the strong Weiss exchange field that arises from the magnetic order in the substance. The field--caused shifts of the conducting bands results in the change in the number of thermally activated carriers, and this change is presumed to be responsible for the resistivity dependences on temperature and magnetic field and for the CMR itself. Employing this model we calculate this hypothetical Weiss field from the experimental data for various CMR manganites employing minimal set of the adjustable parameters, namely two. The obtained Weiss field behaves with temperature and external field similarly to the local magnetization, its supposed source, hence supporting the model.