Raman scattering and phase transitions in ${\mathrm{V}}_2$${\mathrm{O}}_3$ and ${\left({\mathrm{V}}_{1-x}{\mathrm{Cr}}_x\right)}_2{\mathrm{O}}_3$

Phase transitions involving one or more of the three properties: electrical resistivity, crystal structure, and antiferromagnetic ordering, occur in ${\left({\mathrm{V}}_{1-x}{\mathrm{Cr}}_x\right)}_2{\mathrm{O}}_3$ with $x$ of the order of ${10}^{-2\mathrm{}}$. In a previous study of Raman scattering in ${\mathrm{V}}_2$ ${\mathrm{O}}_3$, phonon scattering and a magnon scattering were observed and investigated. We report here studies on ${\left({\mathrm{V}}_{1-x}{\mathrm{Cr}}_x\right)}_2{\mathrm{O}}_3$ with $0<~x<\mathrm{}0.03\mathrm{}$. The effects of Cr content show that energies of the phonons and the magnon are related to the structure and lattice dimensions, and that electrical conduction is not a highly important factor for the lattice properties. We have made also some investigations on the effects of a magnetic field $B=100\mathrm{}$ kG applied to ${\mathrm{V}}_2$ ${\mathrm{O}}_3$. At $T\sim 150$ K the frequency shift of the magnon peak was increased, the intensity of a newly found peak was reduced, and the electrical resistance was not noticeably affected. It seems that magnetic interactions are not a dominant factor in electrical conduction.