标题： 映射（Eu$_{1-x}$Ca$_{x}$)$_{2}$Ir$_{2}$O$_{7}$在金属-绝缘体转变中的结构、磁性和电子行为 显示英文标题

标题： Mapping the structural, magnetic and electronic behavior of (Eu$_{1-x}$Ca$_{x}$)$_{2}$Ir$_{2}$O$_{7}$ across a metal-insulator transition

摘要： 在本研究中，我们采用体电子性质表征和x射线散射/光谱技术，以Ca掺杂为函数，绘制(Eu$_{1-x}$Ca$_{x}$)$_{2}$Ir$_{2}$O$_{7}$的结构、磁性和电子性质。 如预期的那样，金属-绝缘体转变温度，$T_{MIT}$，随着Ca掺杂而降低，直到在2 K时实现金属态。相反，$T_{AFM}$与MIT解耦，并且（可能为短程）AFM序在金属区域中持续存在。 这种解耦被理解为电子相分离状态出现的结果，而这种现象似乎取决于合成方法和稀土位点磁性。 PDF分析表明，电子相分离发生时没有伴随化学相分离或短程晶体学对称性的变化，而同步辐射x射线衍射证实长程晶体学对称性没有变化。 X射线吸收测量证实了 (Eu$_{1-x}$Ca$_{x}$)$_{2}$Ir$_{2}$O$_{7}$的$J_{eff}$ = 1/2 特性。 令人惊讶的是，这些测量还表明存在净电子掺杂，而不是预期的空穴掺杂，这表明存在补偿机制。 最后，XMCD 测量显示 Ir 的磁极化较弱，并且很大程度上不受 Ca 掺杂的影响。 显示英文摘要

摘要： In this study, we employ bulk electronic properties characterization and x-ray scattering/spectroscopy techniques to map the structural, magnetic and electronic properties of (Eu$_{1-x}$Ca$_{x}$)$_{2}$Ir$_{2}$O$_{7}$ as a function of Ca-doping. As expected, the metal-insulator transition temperature, $T_{MIT}$, decreases with Ca-doping until a metallic state is realized down to 2 K. In contrast, $T_{AFM}$ becomes decoupled from the MIT and (likely short-range) AFM order persists into the metallic regime. This decoupling is understood as a result of the onset of an electronically phase separated state, the occurrence of which seemingly depends on both synthesis method and rare earth site magnetism. PDF analysis suggests that electronic phase separation occurs without accompanying chemical phase segregation or changes in the short-range crystallographic symmetry while synchrotron x-ray diffraction confirms that there is no change in the long-range crystallographic symmetry. X-ray absorption measurements confirm the $J_{eff}$ = 1/2 character of (Eu$_{1-x}$Ca$_{x}$)$_{2}$Ir$_{2}$O$_{7}$. Surprisingly these measurements also indicate a net electron doping, rather than the expected hole doping, indicating a compensatory mechanism. Lastly, XMCD measurements show a weak Ir magnetic polarization that is largely unaffected by Ca-doping.