Strongly Correlated Electrons
Strongly correlated materials are a class of materials that exhibit exotic electronic and magnetic properties that cannot be sufficiently accounted for by the non-interacting properties of their individual constituents. The study of such remarkable physical properties and behaviors that arise from correlations is an example of "emergence" science.
Most transition metal oxides belong to this class, with incompletely filled d or f electron shells and narrow bandwidths. The simple picture of a non-interacting electron gas no longer applies here, where strong Coulomb interaction is non-negligible. The most studied example of strong electron correlation is unconventional superconductivity in the copper oxides, which exhibit high transition temperatures due to mechanisms that are still intensely debated. Other remarkable strongly correlated phenomena include colossal magnetoresistence, heavy fermions, Mott insulators, the Kondo effect, and spin-charge ordering. These are some of the interestingly rich subjects that we currently study with tools such as ARPES.
