Joe Checkelsky, Assistant Professor, Department of Physics
A relatively unexplored parameter in topological insulators is electronic correlation. Motivated by the metal-insulator transition observed in the pyrochlore iridates R2Ir2O7 (R is a rare earth) it has been suggested that a combination of weak to moderate correlation effects and large spin-orbit interaction may exist that could give rise to new topologically non-trivial electronic states. In particular, it is expected that this compound’s principle bulk excitations may be described by a 3-dimensional analog of graphene known as a Weyl semimetal with helical excitations in all 3 dimensions with a several exotic and potentially useful properties. Despite these sharp theoretical predictions, the experimental situation is unsettled owing largely to the difficulty in producing single crystal specimens. While optical furnace techniques used for other pyrochlores have thus far proven unsuccessful in producing single crystals, we propose to extend a flux technique reported for R=Eu and Pr across this series to develop high quality single crystals and perform incisive studies of the magnetic transition and transport properties of the electronic ground state. If successful, this study would open the door for other optical and scattering experiments as well as extensions to Os oxides and spinel candidate compounds.