title: Colossal effects in transition metal oxides caused by intrinsic inhomogeneities.
abstract: The influence of quenched disorder on the competition between ordered states separated by a first-order transition is investigated. A phase diagram with features resembling quantum-critical behavior is observed, even using classical models. The low-temperature paramagnetic regime consists of coexisting ordered clusters, with randomly oriented order parameters. Extended to manganites, this state is argued to have a colossal magnetoresistance effect. A scale T(*) for cluster formation is discussed. This is the analog of the Griffiths temperature, but for the case of two competing orders, producing a strong susceptibility to external fields. Cuprates may have similar features, compatible with the large proximity effect of the very underdoped regime.
authors.affiliation: National High Magnetic Field Lab, Florida State University, Tallahassee, Florida 32306, USA.
authors.forename: J
authors.initials: J
authors.lastname: Burgy
authors.forename: M
authors.initials: M
authors.lastname: Mayr
authors.forename: V
authors.initials: V
authors.lastname: Martin-Mayor
authors.forename: A
authors.initials: A
authors.lastname: Moreo
authors.forename: E
authors.initials: E
authors.lastname: Dagotto