Thermal Conductivity of Strongly Correlated Electron Systems

Thermal conductivity via electron and spin degrees of freedom has been a valuable tool to study superconducting properties of high-Tc cuprates and quantum fluctuation of one-dimensional spin liquids. It turned out that presence of metallic quasiparticles is necessary for the superconducting phase transition for the high-Tc cuprates. It is also demonstrated that spin excitations carry a large amount of heat in the one-dimensional quantum magnet, indicating their excellent spatial coherence like phonons and electrons in metals. The thermal conductivity measurement will be useful more generally in studying exotic properties of strongly-correlated electron systems.