Ruthenium-based pyrochlore oxides exemplify a unique material system in which the competition of Mottness ($U$), Hundness ($J_{\mathrm{H}}$), and effective $p-d$ hybridization brings exotic physical characteristics. To understand and manipulate these interactions, we have investigated the structural, magnetic, and electrical properties of the pyrochlore ruthenate ${\mathrm{Y}}_2\mathrm{R}{\mathrm{u}}_2{\mathrm{O}}_7$ and its doped variants ${\left({\mathrm{Y}}_{1-x}\mathrm{C}{\mathrm{a}}_x\right)}_2\mathrm{R}{\mathrm{u}}_2{\mathrm{O}}_7$. The results of our magnetic measurements reveal a systematic suppression of antiferromagnetic (AFM) ordering and increased frustration with the progressive substitution of Ca at the Y site leading to a nonequilibrium glassy magnetic state at low temperature above the doping level of 10%. Moreover, the screening of the net effective moment of Ru in the doped samples, as derived from the experimental results, is attributed to the induced itinerant character of $\mathrm{R}{\mathrm{u}}^{5+}$. Such an effect is also reflected in the substantially reduced electrical resistivity, possibly due to enhanced $d-p$ hybridization. Consistent with the experimental results, density functional theory calculations confirm the bulk AFM ordering and a drop in the band gap of the doped samples. We further claim the low-temperature magnetic state of ${\mathrm{Y}}_2\mathrm{R}{\mathrm{u}}_2{\mathrm{O}}_7$ to possess a noncollinear all-out-type spin configuration, which transforms into a randomized glassy phase upon hole doping.

中文翻译：

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掺杂引起的巡回和轨道杂化的相互作用及其对 (Y1−xCax)2Ru2O7 磁性和输运性质的影响


钌基烧绿石氧化物体现了一种独特的材料系统，其中 Mottness ( $U$ )、Hundness ( $J_{\mathrm{H}}$ ) 和有效 $p-d$ 杂化的竞争带来了奇异的物理性能特征。为了理解和操纵这些相互作用，我们研究了烧绿石钌酸盐 ${\mathrm{Y}}_2\mathrm{R}{\mathrm{u}}_2{\mathrm{O}}_7$ 及其掺杂变体 ${\left({\mathrm{Y}}_{1-x}\mathrm{C}{\mathrm{a}}_x\right)}_2\mathrm{R}{\mathrm{u}}_2{\mathrm{O}}_7$ 的结构、磁性和电学性质。我们的磁性测量结果揭示了反铁磁 (AFM) 有序性的系统抑制，并且随着 Y 位点 Ca 的逐渐取代而增加挫败感，导致在掺杂水平高于 10% 的低温下出现非平衡玻璃态磁态。此外，根据实验结果得出的掺杂样品中Ru的净有效矩的筛选归因于 $\mathrm{R}{\mathrm{u}}^{5+}$ 诱导的巡回特性。这种效应也反映在电阻率的显着降低上，这可能是由于 $d-p$ 杂交的增强。与实验结果一致，密度泛函理论计算证实了体 AFM 有序性和掺杂样品带隙的下降。我们进一步声称 ${\mathrm{Y}}_2\mathrm{R}{\mathrm{u}}_2{\mathrm{O}}_7$ 的低温磁态具有非共线全型自旋构型，在空穴掺杂后转变为随机玻璃相。