Flat Bands and Correlated States in Frustrated Lattice Metals

The notion of an electronic flat band refers to a collectively degenerate set of quantum mechanical eigenstates in periodic solids. The vanishing kinetic energy of flat bands relative to the electron-electron interaction is expected to result in a variety of many-body quantum phases of matter. Here we present recent developments in realizing flat bands in transition element-based frustrated lattice metals. We will present recent experiments in which a partial filling of a flat band is associated with correlated transport and thermodynamic responses. We will also comment on the potential role of band topology and prospects for using similar lattice and orbital engineering to realize new electronic phenomena.