Orbital Rotations induced by Charges of Polarons and Defects in Doped Vanadates

Abstract

We explore the competiton of doped holes and defects that leads to the loss of orbital order in vanadate perovskites. In compounds such as La${}_{1-\mathsf{x}}$Ca${}_{\mathsf{x}}$VO${}_3$ spin and orbital order result from super-exchange interactions described by an extended three-orbital degenerate Hubbard-Hund model for the vanadium $t_{2g}$ electrons. Long-range Coulomb potentials of charged Ca${}^{2+}$ defects and $e$-$e$ interactions control the emergence of defect states inside the Mott gap. The quadrupolar components of the Coulomb fields of doped holes induce anisotropic orbital rotations of degenerate orbitals. These rotations modify the spin-orbital polaron clouds and compete with orbital rotations induced by defects. Both mechanisms lead to a mixing of orbitals, and cause the suppression of the asymmetry of kinetic energy in the $C$-type magnetic phase. We find that the gradual decline of orbital order with doping, a characteristic feature of the vanadates, however, has its origin not predominantly in the charge carriers, but in the off-diagonal couplings of orbital rotations induced by the charges of the doped ions.

10 pages, 7 figures, accepted in Physical Review B

References in corpus (22)

• Theory of Intertwined Orders in High Temperature Superconductors
• Time-resolved Observation and Control of Superexchange Interactions with Ultracold Atoms in Optical Lattices
• Spin-orbital frustrations and anomalous metallic state in iron-pnictide superconductors
• Orbital fluctuations in the different phases of LaVO3 and YVO3
• String excitations of a hole in a quantum antiferromagnet and photoelectron spectrospopy
• Evolution of Spin-Orbital-Lattice Coupling in the $R$VO${}_3$ Perovskites
• Theory of optical spectral weights in Mott insulators with orbital degrees of freedom
• Absence of Hole Confinement in Transition Metal Oxides with Orbital Degeneracy
• Frustration and entanglement in the $t_{2g}$ spin--orbital model on a triangular lattice: valence--bond and generalized liquid states
• Microscopic spinon-chargon theory of magnetic polarons in the t-J model
• Microscopic modelling of doped manganites
• Orbital polaron lattice formation in lightly doped La1-xSrxMnO3
• Ferro-Orbitally Ordered Stripes in Systems with Alternating Orbital Order
• Doping variation of anisotropic charge and orbital dynamics in Y1-xCaxVO3 : Comparison with La1-xSrxVO3
• One-dimensional orbital fluctuations and the exotic magnetic properties of YVO${}_3$
• Rotationally invariant slave-boson and density matrix embedding theory: A unified framework and a comparative study on the 1D and 2D Hubbard Model
• Defect states and spin-orbital physics in doped vanadates Y1-xCaxVO3
• Influence of spin and orbital fluctuations on Mott-Hubbard exciton dynamics in LaVO${}_3$ Thin Films
• Role of rotational symmetry in the magnetism of a multiorbital model
• High Temperature Superconductivity in the Cuprates
• Optical conductivity due to orbital polarons in systems with orbital degeneracy
• Entropy and electronic orders of the three-orbital Hubbard model with antiferromagnetic Hund coupling

Cited by in corpus (1)

• Orbital-selective altermagnetism and correlation-enhanced spin-splitting in transition metal oxides