VO2-BASED SMART WINDOWS

The strong correlations in transition-metal oxides and the orbital modulation (i. e. degeneracy) generate spins and orbitals as low-energy degrees of freedom. Their interplay with both real-charge motion and virtual-charge excitations lead to a fascinating richness of spin–charge–orbital-ordered phases in transition-metal oxides, to striking phenomena like the colossal magnetoresistance in manganites, the switching of charge-ordered phases into metallic phases by applied magnetic field, and many other fascinating effects. The constant and technologically relevant need of adjusting the transition temperature to suit different needs has generated an impressive number of experimental studies. As a general rule, in all published studies the stability of the metallic phase over temperature is associated with the lattice distortion along the metal- metal bond direction in the R-phase and its effect on the bandwidth.1,2