论文标题
Pyrochlore Iridates（Y $ _ {1-x} $ pr $ _X $）$ _ 2 $ _ 2 $ ir $ _2 $ o $ $ _7 $：$ f $ - $ d $交换互动和$ d $ - $ d $ - $ p $ p $ p $ p $ p $ p $ p $ p $ p $ p $ p $ p $ p $ p $
Magnetic and transport properties in pyrochlore iridates (Y$_{1-x}$Pr$_x$)$_2$Ir$_2$O$_7$: The role of $f$-$d$ exchange interaction and $d$-$p$ orbital hybridization
论文作者
论文摘要
$ f $ - $ d $磁性交换交互被认为是pyrochlore Iridates许多外来拓扑阶段的关键要素。在这里，我们研究了掺杂的pyrochlore iRITADE中的结构，磁性和电子特性的演变，（y $ _ {1-x} $ pr $ _x $）$ _ 2 $ _ 2 $ ir $ _2 $ o $ $ _7 $。除几何挫败感外，pyrochlore虹膜源以其活跃的自旋轨道耦合效果而闻名。 pr $^{3+} $（4 $ f^2 $）代替非磁性y $^{3+} $（4 $ d^0 $）是一种磁性掺杂，它为研究$ f $ -d $ d $交换相互作用提供了理想的平台，而无需更改ir-sublattice。通过PR替代，系统保留其原始的立方结构对称性，但局部结构参数显示出掺杂浓度$ x $的进化。 y $ _2 $ ir $ _2 $ o $ _7 $的强大磁性胰岛状态大大削弱，而pr $ _2 $ _2 $ _2 $ _2 $ o $ _7 $（$ x $ = 1.0）显示出pragragnetic-metallic的行为。对于$ x $ = 0.8样品，观察到金属 - 绝缘体过渡。人们认为，磁性和电子特性的这种演变是由局部PR-4 $ F $与巡回IR-5 $ D $电子之间的交换相互作用以及通过在XAS研究中观察到的IR- $ T_ {2G} $和（基础）O- P $ orbitals之间的杂交增加而引起的。绝缘材料的电阻率遵循幂律行为，其指数下降了$ x $。对于低温下的一系列样品，观察到一个负磁磁性，而磁路震动显示在较高场处的二次场依赖性。
The $f$-$d$ magnetic exchange interaction is considered to be a key ingredient for many exotic topological phases in pyrochlore iridates. Here, we have investigated the evolution of structural, magnetic and electronic properties in doped pyrochlore iridate, (Y$_{1-x}$Pr$_x$)$_2$Ir$_2$O$_7$. Apart from geometrical frustration, pyrochlore iridates are well known for its active spin-orbit coupling effect. The substitution of Pr$^{3+}$ (4$f^2$) for the nonmagnetic Y$^{3+}$ (4$d^0$) acts as a magnetic doping, which provides an ideal platform to study $f$-$d$ exchange interaction without altering the Ir-sublattice. With Pr substitution, system retains its original cubic structural symmetry but the local structural parameters show an evolution with the doping concentration $x$. The robust magnetic-insulating state in Y$_2$Ir$_2$O$_7$ is drastically weakened, while Pr$_2$Ir$_2$O$_7$ ($x$ = 1.0) shows a paramagnetic-metallic behavior. A metal-insulator transition is observed for $x$ = 0.8 sample. This evolution of magnetic and electronic properties are believed to be induced by an exchange interaction between localized Pr-4$f$ and itinerant Ir-5$d$ electrons as well as by an increased hybridization between Ir-$t_{2g}$ and (basal) O-$p$ orbitals as observed in XAS study. The resistivity in insulating materials follows a power-law behavior with a decreasing exponent with $x$. A negative magnetoresistance is observed for present series of samples at low temperature and where the magnetoresistance shows a quadratic field dependence at higher fields.
