Orbital disorder induced by charge fluctuations in vanadium spinels

Area of Science:

• Condensed Matter Physics
• Materials Science
• Quantum Chemistry

Background:

• Recent experiments on vanadium spinels (AV2O4) indicate increasing electronic delocalization with smaller cation sizes.
• Understanding orbital ordering (OO) is crucial for predicting material properties in strongly correlated systems.
• The interplay between magnetic ordering and orbital degrees of freedom in Mott insulators requires further investigation.

Purpose of the Study:

• To investigate the evolution of orbital ordering (OO) in multiorbital Hubbard models.
• To analyze the transition between strong and intermediate coupling regimes in vanadium spinels.
• To understand the influence of magnetic ordering on orbital degrees of freedom.

Main Methods:

• Utilized a multiorbital Hubbard Hamiltonian to model electronic interactions.
• Studied the system's behavior across the strong and intermediate coupling regimes.
• Analyzed the impact of magnetic ordering on orbital ordering and charge fluctuations.

Main Results:

• Magnetic ordering in the Mott insulating state significantly suppresses orbital ordering.
• Enhanced charge fluctuations along ferromagnetic bonds contribute to the suppression of OO.
• Low orbital double occupancy at the transition point suggests a crossover region with disordered orbital degrees of freedom.

Conclusions:

• The study elucidates the suppression mechanism of orbital ordering in vanadium spinels.
• Results highlight the crossover between strong and intermediate coupling regimes where orbital disorder prevails.
• Findings provide insights into the complex electronic and magnetic behavior of correlated materials.