Colossal magnetoresistance

The CMR effect or colossal magnetoresistive effect (English colossal magnetoresistance, CMR) is a physical anomaly in the electrical resistance of some materials in the presence of a magnetic field changed massively. This is because that with these materials for a sufficiently large field is by shifting the band structure of the circuit to the isolator. It belongs to the group of the magnetoresistive effects.

The effect was first discovered in 1950 by G. H. Jonker and JH van Santen. The effect occurs in mixed-valence manganese oxides, for example. Shortly after its discovery, a theoretical description could be found within the framework of the double exchange model, the kinetic exchange processes with the spin orientation of neighboring Mn moments are correlated. Important experimental work by Volger, Wollan and Koehler, and later by Jirak et al. and pollert et al. advanced the understanding of the effect. The renewed boom in research on the magnetoresistive effects and the work of RM Kusters, R. Helm Holt and Jin et al. led in the early 1990s to many other works, and a deeper understanding of the basic effects.