Strongly-correlated crystal-field approach to heavy-fermion compounds and to 3d oxides

The description of electronic and magnetic properties of real compounds like LaMnO$_{3}$, LaCoO$_{3}$, Na$_{2}$V$_{3}$O$_{7}$, FeO, NdAl$_{2}$ and ErNi$_{5}$ as well as heavy-fermion superconductor UPd$_{2}$Al$_{3}$ and heavy-fermion metal YbRh$_{2}$Si$_{2}$, both zero-temperature ground state properties and thermodynamics, will be presented pointing out the existence of a discrete atomic-like low-energy, in the meV scale, electronic structure. This low-energy many-electron discrete atomic-like electronic structure is governed by very strong electron correlations, predominantly on-site, by the intra-atomic spin-orbit coupling and by details of the local surrounding (crystal-field interactions), but later is modified by inter-site interactions. Our studies indicate that there is the highest time to ``unquench'' the orbital moment in solid state physics in description of 3d-/4f-/5f-atom containing compounds and that heavy-fermion phenomena are of the relativistic origin.