2008/03/27 by J. Fujioka, S. Miyasaka, Y. Tokura
Chemistry · Materials Science · Physics and Astronomy · #Advanced Condensed Matter Physics #Chemistry #Condensed matter physics #Crystal structure #Crystallography #Doping #Electronic and Structural Properties of Oxides #Magnetic and transport properties of perovskites and related materials #Optical conductivity #Orthorhombic crystal system #Physics #cond-mat.str-el
paper · pdf · doi:10.1103/physrevb.77.144402
10 pages, 9 figures
arxiv created 2008/03/27 · openalex publication_date 2008/04/02 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
The doping variation of charge and orbital dynamics in perovskite-type Y_1\ensuremath-xCaxVO3 (0\ensuremath≤x\ensuremath≤0.1) is investigated by measurements of the optical conductivity and Raman scattering spectra in comparison to the larger bandwidth system La_1\ensuremath-xSrxVO3. We also take into consideration the magnitude of the GdFeO3-type orthorhombic lattice distortion, which is large and small in Y_1\ensuremath-xCaxVO3 and La_1\ensuremath-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 polaronlike state. The hole dynamics in Y_1\ensuremath-xCaxVO3 is nearly isotropic up to the doping level of the orbital order-disorder transition, while that in La_1\ensuremath-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 polaronlike 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 La_1\ensuremath-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 spin ordering and G-type orbital ordering.