Strongly correlated systems and their excitations: a back-of-the-envelope introduction

Many quantum materials displaying interesting phenomena like magnetism or unusual superconductivity are characterized by strong electron-electron interactions. As a consequence, their fundamental properties and the underlying electronic excitations can no longer be described within the independent particle picture (i.e., band picture), as the dynamics of the electrons become strongly entangled, i.e. correlated. While this may lead to complex many-body states, the conceptual framework for their understanding is not so complicated and directly related to experimental probes such as photoemission spectroscopy.

In his lecture Prof. Tjeng will illustrate the differences of the one-particle and many-body pictures by using one of the simplest strongly correlated electron systems available: the hydrogen molecule.