Optical study of MgTi2O4: Evidence for an orbital-Peierls state

[摘要] Dimension reduction due to the orbital ordering has recently been proposed to explain the exotic charge, magnetic, and structural transitions in some three-dimensional transitional metal oxides. We present optical measurement on a spinel compound MgTi2O4 which undergoes a sharp metal-insulator transition at 240 K, and show that the spectral change across the transition can be well understood from the proposed picture of one-dimensional Peierls transition driven by the ordering of d(yz) and d(zx) orbitals. We further elaborate that the orbital-driven instability picture applies also very well to the optical data of another spinel CuIr2S4 reported earlier.

[发布日期] 2006-12-01

[关键词] PHASE-TRANSITION;METAL;INSULATOR;NATISI2O6;CUIR2S4;SYSTEMS