Pressure-dependent Raman scattering study of CoV$_2$O$_4$*

The $A$V$_2$O$_4$ ($A$ = Cd, Mn, Mg, Zn, Co) spinel family provides a fertile ground to explore the crossover between electron localization and itinerancy, which can be tuned with chemical ($A$-site substitution) and/or physical pressure. CoV$_2$O$_4$ resides closest to the predicted itinerant electron limit for the vanadium spinel family. Recent experiments have shown the existence of a critical V-V separation by inducing a metallic transition in CoV$_2$O$_4$ with a pressure of $\sim$6 GPa.\footnote{A. Kismarahardja, \textit{et al}., Phys. Rev. Lett. \textbf{106}, 056602 (2011).} While the structure of CoV$_2$O$_4$ has been theoretically suggested to remain cubic through the metallic transition,\footnote{R. Kaur, \textit{et al}., J. Phys.: Condens. Matter \textbf{26}, 045505 (2014).} no structural measurements under pressure have been performed. Raman spectroscopy is well suited to address this issue, as it is sensitive to even subtle structural changes. In this presentation, I present a pressure-dependent Raman scattering study of CoV$_2$O$_4$ to elucidate the role the structure plays in the metallic transition.