Role of Orbitals in the Physics of Correlated Electron Systems

TL;DR

This paper reviews the significance of orbital degrees of freedom in strongly correlated electron systems, highlighting recent developments and their impact on understanding complex material properties.

Contribution

It provides a concise summary of key concepts and recent advances in the role of orbitals in correlated electron physics.

Findings

Orbital degrees of freedom critically influence material properties.

Recent developments have advanced understanding of orbital effects.

Orbital interactions are essential in transition metal oxides.

Abstract

Rich properties of systems with strongly correlated electrons, such as transition metal oxides, is largely connected with an interplay of different degrees of freedom in them: charge, spin, orbital ones, as well as crystal lattice. Specific and often very important role is played by orbital degrees of freedom. In this comment I will shortly summarize the main concepts and discuss some of the well-known manifestations of orbital degrees of freedom, but will mostly concentrate on a recent development in this field.