Comment on ?Orbital ordering and orbital fluctuations in transition metal oxides? [phys. stat. sol. (b)236, No. 2, 281-288 (2003)]

2005 ◽  
Vol 242 (4) ◽  
pp. 962-962 ◽  
Author(s):  
R. J. Radwanski ◽  
Z. Ropka
Keyword(s):  
Transition Metal ◽  
Metal Oxides ◽  
Transition Metal Oxides ◽  
Orbital Ordering

scholarly journals ORBITAL INSULATORS AND ORBITAL ORDER–DISORDER INDUCED METAL–INSULATOR TRANSITION IN TRANSITION-METAL OXIDES

2007 ◽  
Vol 21 (05) ◽  
pp. 691-706 ◽  
Author(s):  
DONG-MENG CHEN ◽  
LIANG-JIAN ZOU
Keyword(s):  
Transition Metal ◽  
Metal Oxides ◽  
Transition Metal Oxides ◽  
Thermal Fluctuation ◽  
Insulator Transition ◽  
Orbital Ordering ◽  
Excitation Spectra ◽  
Metal Insulator Transition ◽  
Orbital Order ◽  
Metal Insulator

The role of orbital ordering on metal–insulator transition in transition-metal oxides is investigated by the cluster self-consistent field approach in the strong correlation regime. A clear dependence of the insulating gap of single-particle excitation spectra on the orbital order parameter is found. The thermal fluctuation drives the orbital order–disorder transition, diminishes the gap and leads to the metal–insulator transition. The unusual temperature dependence of the orbital polarization in the orbital insulator is also manifested in the resonant X-ray scattering intensity.

Charge and orbital ordering in transition metal oxides

2002 ◽  
Vol 12 (9) ◽  
pp. 257-257
Author(s):  
D. Khomskii
Keyword(s):  
Transition Metal ◽  
Metal Oxides ◽  
Transition Metal Oxides ◽  
Degrees Of Freedom ◽  
Relative Role ◽  
Strongly Correlated ◽  
Orbital Ordering ◽  
Spin Orbital ◽  
Electron Phonon Interaction ◽  
Frustrated Systems

Transition metal oxides with strongly correlated d-electrons show an astonishing variety of properties. This is largely determined by an interplay of different degrees of freedom: charge, spin, orbital, lattice ones. Often there appear in them various superstructures. In this talk I will consider different types of superstructures in transition metal oxides, especially charge and orbital ordering, willdiscuss the main mechanisms leading to their formation and consider specific examples of superstructures in manganites, cobaltites and in some frustrated systems. Relative role of purely electronic mechanisms and of the electron-phonon interaction will be discussed. In particular, I will show that the elastic interactions can naturally lead to different superstructures, including stripes. Special features of charge and, especially, orbital ordering in frustrated systems, where frustrations may be caused both by the geometric structure of the lattice and by the special features of orbital interactions, will be considered, and it will be shown that the order-from-disorder mechanism can lead to a unique ordered ground state in many of these cases..

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