Possible Coexistence of Local Itinerancy and Global Localization in a Quasi-One-Dimensional Conductor

In the chain compound Pr⁡Ba2Cu4O8 localization appears simultaneously with a dimensional crossover in the electronic ground state when the scattering rate in the chains exceeds the hopping rate between the chains. Here we report the discovery of a large, transverse magnetoresistance in Pr⁡Ba2Cu4O8 in the localized regime. This result suggests a novel form of localization whereby electrons retain their metallic (quasi-one-dimensional) character over a microscopic length scale despite the fact that, macroscopically, they exhibit localized (one-dimensional) behavior.