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We measured the optical properties of mixed valent vanadium oxide nanoscrolls and their metal exchanged derivatives in order to investigate the charge dynamics in these compounds. In contrast to the prediction of a metallic state for the metal exchanged derivatives within a rigid band model, we find that the injected charges in Mn$^{2+}$ exchanged vanadium oxide nanoscrolls are pinned. A low-energy electronic excitation associated with the pinned carriers appears in the far infrared and persists at low temperature, suggesting that the nanoscrolls are weak metals in their bulk form, dominated by inhomogeneous charge disproportionation and Madelung energy effects.
Recently amorphous oxide semiconductors (AOS) have gained commercial interest due to their low-temperature processability, high mobility and areal uniformity for display backplanes and other large area applications. A multi-cation amorphous oxide (a-
Vanadium dioxide (VO$_2$) undergoes a metal-insulator transition (MIT) at 340 K with the structural change between tetragonal and monoclinic crystals as the temperature is lowered. The conductivity $sigma$ drops at MIT by four orders of magnitude. Th
Precise control of the chemical valence or oxidation state of vanadium in vanadium oxide thin films is highly desirable for not only fundamental research, but also technological applications that utilize the subtle change in the physical properties o
We investigated the specific electronic energy deposition by protons and He ions with keV energies in different transition metal nitrides of technological interest. Data were obtained from two different time-of-flight ion scattering setups and show e
Sparse matter is characterized by regions with low electron density and its understanding calls for methods to accurately calculate both the van der Waals (vdW) interactions and other bonding. Here we present a first-principles density functional the