Influence of Structural Disorder on Hollandites AxRu4O8 (A+ = K, Rb, Rb1–xNax)

Structural disorder can play an important role in the electrical properties of correlated materials. In this work we examine the average and local disorder in hollandites AxRu4O8 (A+ = K, Rb, Rb1–xNax) through neutron total scattering techniques. Samples with A+ = Rb, Rb1–xNax exhibit the largest amount of local disorder as evidenced by higher atomic displacement parameters, and as a result, a weakened temperature dependence of the resistivity is observed upon cooling as compared to KxRu4O8. All samples exhibit anisotropic resistivity that is dominated by metallic conductivity at lower temperatures, and this is corroborated by Pauli paramagnetic behavior throughout the measured temperature regime.

结构无序对强关联材料（correlated materials）的电学性能具有重要影响。本工作采用中子全散射技术，对hollandite型AxRu4O8（hollandite，A+为K、Rb、Rb₁₋ₓNaₓ）的平均无序与局域无序特征展开系统研究。其中A+为Rb、Rb₁₋ₓNaₓ的样品展现出最为显著的局域无序，该结论可通过更高的原子位移参数（atomic displacement parameters）得到佐证；相较于KₓRu4O8，此类样品在降温过程中电阻率的温度依赖性显著减弱。所有样品均呈现各向异性电阻率特征，且在低温区间以金属导电为主；这一结果与整个测量温度范围内观测到的泡利顺磁（Pauli paramagnetic）行为相吻合。