Abstract
Anomalous low temperature electronic and structural behavior has been discovered in . The structure [space group , , , ] and metallic conductivity at 290 K are similar to those of and other ruthenate perovskites, but a sharp metal-insulator transition at which the resistivity increases by 4 orders of magnitude is discovered at 90 K. This is accompanied by a first-order structural transition to an phase [, , at 25 K] that shows a coupling of orbital order to distortions from orbital hybridization. The to transition is an unconventional reversal of the group-subgroup symmetry relationship. No long range magnetic order is evident down to 1.5 K. Calculations show that Pb and Ru orbital hybridization and strong spin-orbit coupling are significant.
- Received 20 November 2008
DOI:https://doi.org/10.1103/PhysRevLett.102.046409
©2009 American Physical Society