Crossover from Positive to Negative Colossal Magnetoresistance

In the past few years, the study of colossal magnetoresistance has unveiled fascinating new physics that has had a major impact on the understanding of strongly correlated electron systems. This proposal outlines research to investigate a new mechanism for colossal magnetoresistance (CMR) recently discover in doped ZnCr2Se4, which is vastly different to that reported for both manganate perovskites and pyrochlores, with a significant effect observed in low fields as well as an unprecedented crossover from positive to negative colossal magnetoresistance (MR > 90 %) as a function of both field and temperature.