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arXiv · 0811.3378

Metal-Insulator Transition and Orbital Order in PbRuO3

S. A. J. Kimber·J. A. Rodgers·H. Wu·C. A. Murray·D. N. Argyriou·A. N. Fitch·D. I. Khomskii·J. P. Attfield
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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

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S. A. J. Kimber, J. A. Rodgers, H. Wu, C. A. Murray, D. N. Argyriou, A. N. Fitch, D. I. Khomskii, J. P. Attfield. 2008-11-20. Metal-Insulator Transition and Orbital Order in PbRuO3. https://doi.org/10.1103/physrevlett.102.046409

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