Solid State Physics

Before the year 1937 the only known concept of classifying metals, insulators and semiconductors was based on the filling of electronic bands [?,?]. On the famous Bristol conference in 1937 though de Boer and Verway [?] reported that many transition metal oxides with partially filled d-electron bands do not fit into this picture. Experiments revealed that they are either poor conductors or even insulators in spite of their partially filled bands. Soon later Peierls [?] discovered that in some special cases the electron-electron correlations arising from strong coulomb repulsion can prevent the electrons from moving thus yielding an insulator. This article founded the field of strongly correlated electrons.