Searching for the Slater Transition in the Pyrochlore Cd₂Os₂O₇ with Infrared Spectroscopy

Original · EN

Infrared reflectance measurements were made on the single crystal pyrochlore Cd₂Os₂O₇ in order to examine the transformations of the electronic structure and crystal lattice across the boundary of the metal insulator transition at TMIT=226K. All predicted IR active phonons are observed in the conductivity over all temperatures and the oscillator strength is found to be temperature independent. These results indicate that charge ordering plays only a minor role in the MIT and that the transition is strictly electronic in nature. The conductivity shows the clear opening of a gap with 2Δ=5.2kBTMIT. The gap opens continuously, with a temperature dependence similar to that of BCS superconductors, and the gap edge having a distinct σ(ω)ω¹/² dependence. All of these observables support the suggestion of a Slater transition in Cd₂% Os₂O₇.