Y1-xCaxVO3中各向异性电荷和轨道动力学的掺杂变化：与La1-xSrxVO3的比较
Doping variation of anisotropic charge and orbital dynamics in Y1-xCaxVO3 : Comparison with La1-xSrxVO3
摘要：
通过测量Y1-xCaxVO 3（0<x<0.1）的电导率和拉曼散射光谱，研究了掺杂对钙钛矿型Y1-xCaxVO 3（0<x<0.1）中电荷和轨道动力学的影响，并与宽带La 1-xSrxVO 3进行了比较.我们还考虑到GdFeO 3型正交晶格畸变的大小，这是大的和小的Y1-xCaxVO 3和La 1-xSrxVO 3，分别，并讨论其对电荷动力学演化的影响。光电导谱表明，掺杂空穴局域性好，形成小的类极化子态。Y1-xCaxVO 3中的空穴动力学在轨道有序-无序转变的掺杂水平下几乎是各向同性的，而La 1-xSrxVO 3中的空穴动力学在轻掺杂区域由于一维轨道交换作用而呈现各向异性.在空穴动力学的差异的可能起源进行了讨论，在本地晶格畸变，这是诱导的小极化子的状态的形成，并成为更重要的减少单电子带宽。此外，在名义上的C型自旋和$G$型轨道有序相的光学莫特间隙激发是不同的，从La 1-xSrxVO 3在其强度和光谱形状。这表明正交晶格畸变分别增强了纯C型和G型自旋和轨道有序的修改。Raman散射谱的系统研究表明，在低温下，名义上C型SO和G型OO的掺杂诱导相存在动态的G型自旋和C型轨道关联。
英文摘要：
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.
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