Department of Materials Science and engineering, Dankook University, Cheonan, 31116, Republic of Korea.
Department of Physics, Kunsan National University, Gunsan 54150, Republic of Korea.
Phys Chem Chem Phys. 2023 Feb 1;25(5):3942-3949. doi: 10.1039/d2cp05127c.
The decisive physical parameters on electrical conduction in a LaVO Mott-Hubbard system are systematically investigated by analyzing pure, Ca-, and Sr-doped samples. The Rietveld refinement of the X-ray diffraction data indicates that a drastic change occurs along the -axis to reduce the octahedral tilt thereby relaxing the distortion for the doped compounds, in contrast to an insignificant change in the in-plane distortion. From electrical, optical, and photoemission measurements, both Ca and Sr-doping in LaVO induce insulator to metal transitions under a similar hole carrier concentration as suppressing the Mott-gap excitation. Fitting results on temperature-dependent resistivity based on various conduction models indicate that the most localized conduction behavior takes place for the highly distorted pure LaVO, while disordered Fermi liquid behavior starts to appear for moderately distorted Ca-doped LaVO. The least distorted Sr-doped LaVO exhibits fully delocalized conduction governed by a non-Fermi-liquid-like behavior in the whole temperature range. Our analysis indicates that the difference in the transport mechanism arises from the differing degree of hybridization of the V 3d and O 2p states in the pure and doped systems, strongly associated with the structural distortion.
通过分析纯 LaVO、Ca 掺杂和 Sr 掺杂样品，系统研究了 LaVO Mott-Hubbard 体系中电传导的决定性物理参数。X 射线衍射数据的 Rietveld 精修表明，掺杂化合物沿轴发生剧烈变化，从而减小八面体倾斜，弛豫了扭曲，而面内扭曲变化不大。从电学、光学和光发射测量来看，与抑制 Mott 间隙激发一样，Ca 和 Sr 在 LaVO 中的掺杂在相似的空穴载流子浓度下诱导绝缘体到金属转变。基于各种传导模型的温度相关电阻率拟合结果表明，对于高度扭曲的纯 LaVO，最局域化的传导行为发生，而对于中度扭曲的 Ca 掺杂 LaVO，无序费米液体行为开始出现。在整个温度范围内，具有最小扭曲的 Sr 掺杂 LaVO 表现出完全离域的传导，由非费米液体样行为控制。我们的分析表明，输运机制的差异源于纯和掺杂体系中 V 3d 和 O 2p 态的杂化程度不同，这与结构扭曲密切相关。
