Doping variation of anisotropic charge and orbital dynamics in Y1-xCaxVO3 : Comparison with La1-xSrxVO3

Abstract

The doping variation of charge and orbital dynamics in perovskite-type Y1-xCaxVO3 (0<x<0.1) is investigated by measurements of the optical conductivity and Raman scattering spectra in comparison with the larger-bandwidth system La1-xSrxVO3. We also take into consideration the magnitude of the GdFeO3-type orthorhombic lattice distortion, which is large and small in Y1-xCaxVO3 and La1-xSrxVO3, respectively, and discuss its effect on the evolution of charge dynamics. The optical conductivity spectra show that the doped hole is well localized and forms the small polaron like state. The hole dynamics in Y1-xCaxVO3 is nearly isotropic up to the doping level of the orbital order-disorder transition, while that in La1-xSrxVO3 is anisotropic in the lightly doped region due to the one-dimensional orbital exchange interaction. The possible origin of the difference in the hole dynamics is discussed in terms of the local lattice distortion, which is induced by the formation of the small polaron like state and becomes more significant for the reduced one-electron bandwidth. In addition, the optical Mott-gap excitation in the nominally C-type spin and $G$-type orbital ordered phase is distinct from that for La1-xSrxVO3 in its intensity and spectral shape. This suggests that the orthorhombic lattice distortion enhances the modification of the spin and orbital ordering from the pure C-type and G-type, respectively. The systematic study of Raman scattering spectra has shown that the dynamic G-type spin and C-type orbital correlation subsists at low temperatures in the doping induced phase of the nominally C-type SO and G-type OO.

10 pages, 9 figures

References in corpus (5)

• Orbital fluctuations in the different phases of LaVO3 and YVO3
• Theory of optical spectral weights in Mott insulators with orbital degrees of freedom
• Structural, electronic, and magneto-optical properties of YVO${}_3$
• One-Dimensional Confinement and Enhanced Jahn-Teller Instability in LaVO${}_3$
• Entropy Driven Dimerization in a One-Dimensional Spin-Orbital Model

Cited by in corpus (8)

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• Spin-Orbital Order Modified by Orbital Dilution in Transition Metal Oxides: From Spin Defects to Frustrated Spins Polarizing Host Orbitals
• Defect states and spin-orbital physics in doped vanadates Y1-xCaxVO3
• Spin-orbital order in LaMnO${}_3$: $d-p$ model study
• Exotic Spin-Orbital Physics in Hybrid Oxides
• Orbital Rotations induced by Charges of Polarons and Defects in Doped Vanadates
• Rare collapse of fermionic quasiparticles upon coupling to local bosons