Abstract
Electronic instabilities in transition metal compounds can lead to ground states containing orbital molecules when direct metal-metal orbital interactions occur. The largest reported orbital molecules are V717+ heptamers that emerge below a 700 K charge ordering transition in the spinel AlV2O4. However, x-ray total scattering analysis shows that the apparent heptamers are actually pairs of spin-singlet V39+ trimers and V48+ tetramers, and that these orbital molecules persist to at least 1100 K although they become `hidden' by disorder in the average cubic structure above the charge ordering transition.
Highlights
Electronic instabilities in transition metal compounds may lead to ground states containing orbital molecules when direct metal-metal orbital interactions occur
The largest orbital molecules claimed to date are heptameric clusters, reported in AlV2O4 below a charge and orbital ordering transition accompanied by a rhombohedral to cubic structural distortion at TCO = 700 K [17]
Similar pair distribution function (PDF) studies of CuIr2S4 and VO2 have reported that the orbital dimers disappear from both the long range and local structure above their transition temperatures [24,25]
Summary
Electronic instabilities in transition metal compounds may lead to ground states containing orbital molecules when direct metal-metal orbital interactions occur. Our X-ray total scattering analysis of AlV2O4 between 300 and 1100 K reveals a very different picture as the postulated heptamers are found to be pairs of spin-singlet V39+ trimers and V48+ tetramers, and these orbital molecules persist to at least 1100 K in a disordered high temperature cubic phase.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
