Orbital degeneracy and Mott transition in Mo pyrochlore oxides

Abstract

We present our theoretical results on an effective two-band double-exchange model on a pyrochlore lattice for understanding intricate phase competition in Mo pyrochlore oxides. The model includes the twofold degeneracy of $e_g^{\prime }$ orbitals under trigonal field splitting, the interorbital Coulomb repulsion, the Hund's-rule coupling between itinerant $e_g^{\prime }$ electrons and localized $a_{1g}$ spins, and the superexchange antiferromagnetic interaction between the $a_{1g}$ spins. By Monte Carlo simulation with treating the Coulomb repulsion at an unrestricted-type mean-field level, we obtain the low-temperature phase diagram as functions of the Coulomb repulsion and the superexchange interaction. The results include four dominant phases with characteristic spin and orbital orders and the metal-insulator transitions among them. The insulating region is characterized by a `ferro'-type orbital ordering of the $e_g^{\prime }$ orbitals along the local $<111>$ axis, irrespective of the spin ordering.

6 pages, proceedings for ICFCM

References in corpus (4)

• Magnetic Pyrochlore Oxides
• Phase competition in the double-exchange model on the frustrated pyrochlore lattice
• Electronic phase separation in the pyrochlore double-exchange model
• Ferromagnetic transition in the double-exchange model on the pyrochlore lattice

Cited by in corpus (5)

• Spin-orbital frustration in pyrochlores A2Mo2O7
• Mott-Hubbard transition and spin-liquid state on the pyrochlore lattice
• Spin-orbital liquids and insulator-metal transitions on the pyrochlore lattice
• Mott transition and anomalous resistive state in the pyrochlore molybdates
• Orbital Mott transition in two dimensional Pyrochlore lattice