Abstract
A paramagnetic metal to nonmagnetic insulator transition at is reported for the -pyrochlore oxide , accompanied by a first order structural transition that creates oriented chains in the pyrochlore lattice. Comparison of , which has 1 electron per 2 W sites, to the fully analog shows that the transitions are electronically driven. Corefinement of high resolution synchrotron x-ray and neutron diffraction data shows that the structural distortion that creates the W chains cannot be attributed to simple charge or orbital ordering. Density functional theory calculations suggest that the phase transition is driven by a sharply peaked electronic density of states near the Fermi energy in the cubic -pyrochlore phase. A further electronic instability is required to create the insulating ground state.
- Received 3 January 2013
DOI:https://doi.org/10.1103/PhysRevLett.110.166402
© 2013 American Physical Society