The field of condensed matter physics aims at exploring the emergent properties of matter at large scales. In Shen Group, we are especially interested in understanding the fascinating properties of quantum materials, for which semiclassical treatment is not sufficient and quantum effects play an important role.
An important class of quantum materials is the strongly correlated electron systems. They exhibit exotic electronic and magnetic properties that cannot be sufficiently accounted for by the non-interacting properties of their individual constituents. Most transition metal oxides belong to this class, with partially 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 iron-based superconductors, colossal magnetoresistance, heavy fermions, Mott insulators, the Kondo effect, and spin-charge ordering.