Uchida M, Fujioka J, Onose Y, Tokura Y
Department of Applied Physics, University of Tokyo, Tokyo 113-8656, Japan.
Phys Rev Lett. 2008 Aug 8;101(6):066406. doi: 10.1103/PhysRevLett.101.066406.
Charge dynamics of (Ti1-xVx)2O3 with x=0-0.06 has been investigated by measurements of charge transport and optical conductivity spectra in a wide temperature range of 2-600 K with the focus on the thermally and doping induced insulator-metal transitions (IMTs). The optical conductivity peaks for the interband transitions in the 3d t_{2g} manifold are observed in both the insulating and metallic states, while their large variation (by approximately 0.4 eV) with change of temperature and doping level scales with that of the Ti-Ti dimer bond length, indicating the weakened singlet bond in the course of IMTs. The thermally and V-doping induced IMTs are driven with the increase in carrier density by band crossing and hold doping, respectively, in contrast with the canonical IMT of correlated oxides accompanied by the whole collapse of the Mott gap.
通过在2 - 600 K的宽温度范围内测量电荷传输和光导率光谱，研究了x = 0 - 0.06时(Ti1-xVx)2O3的电荷动力学，重点关注热诱导和掺杂诱导的绝缘体 - 金属转变（IMT）。在绝缘态和金属态中均观察到3d t_{2g} 多重态中间带跃迁的光导率峰，而它们随温度和掺杂水平变化的大幅变化（约0.4 eV）与Ti - Ti二聚体键长的变化成比例，表明在IMT过程中单重键减弱。与相关氧化物典型的IMT伴随着莫特能隙的完全崩塌不同，热诱导和V掺杂诱导的IMT分别由能带交叉和保持掺杂导致载流子密度增加而驱动。
