Metal-Insulator Transition and Orbital Order in PbRuO3

Abstract

Anomalous low temperature electronic and structural behaviour has been discovered in PbRuO3. The structure (space group Pnma, a = 5.56314(1), b = 7.86468(1), c = 5.61430(1) A) and metallic conductivity at 290 K are similar to those of SrRuO3 and other ruthenate perovskites, but a sharp metal-insulator transition at which the resistivity increases by four orders of magnitude is discovered at 90 K. This is accompanied by a first order structural transition to an Imma phase (a = 5.56962(1), b = 7.74550(1), c = 5.66208(1) A at 25 K) that shows a coupling of Ru4+ 4d orbital order to distortions from Pb2+ 6s6p orbital hybridization. The Pnma to Imma transition is an unconventional reversal of the group-subgroup symmetry relationship. No long range magnetic order is evident down to 1.5 K. Electronic structure calculations show that hybridization of Pb 6s6p and Ru 4d orbitals and strong spin-orbit coupling stabilise this previously hidden ground state for ruthenate perovskites

References in corpus (1)

• Orbitally driven spin-singlet dimerization in $S$=1 La${}_4$Ru${}_2$O${}_{10}$

Cited by in corpus (3)

• Mixed-Valence-Driven Heavy-Fermion Behavior and Superconductivity in KNi${}_2$Se${}_2$
• Spin-Orbital Order Modified by Orbital Dilution in Transition Metal Oxides: From Spin Defects to Frustrated Spins Polarizing Host Orbitals
• Lattice dynamics across the ferroelastic phase transition in Ba2ZnTeO6: A Raman and first-principles study