Spontaneous Hall effect enhanced by local Ir moments in epitaxial Pr2Ir2O7 thin films
Spontaneous Hall effect enhanced by local Ir moments in epitaxial Pr2Ir2O7 thin films
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DOI：
10.1103/physrevb.101.104405
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发表时间：
2019-12
影响因子：
3.7
通讯作者：
Lu Guo;N. Campbell;Yongseong Choi;Jong-Woo Kim;P. Ryan;H. Huyan;Linze Li;T. Nan;Jongwuk Kang;C. Sundahl;Xiaoqing Pan;M. Rzchowski;C. Eom
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文献类型：
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作者：
Lu Guo;N. Campbell;Yongseong Choi;Jong-Woo Kim;P. Ryan;H. Huyan;Linze Li;T. Nan;Jongwuk Kang;C. Sundahl;Xiaoqing Pan;M. Rzchowski;C. Eom
稀土烧绿石铱酸盐（RE 2 Ir 2 O 7）由两个互穿的阳离子亚晶格组成，RE具有高度阻挫的磁矩，而铱具有扩展的导电轨道，通过自旋-轨道相互作用显著混合。这两个亚晶格的共存和耦合为发现和操纵量子现象创造了一个景观，如拓扑霍尔效应，无质量导带和量子临界性。薄膜允许通过诸如应变之类的降低电阻的效应来扩展对材料系统的控制。虽然体Pr_2Ir_2O_7在1.5K以下表现出自发的滞后霍尔效应，但我们在通过固相外延合成的（111）YSZ衬底上的外延薄膜中观察到了在高达15 K的高温下的效应。类似的散装，缺乏可观察到的长程磁性秩序的薄膜点的拓扑起源。我们使用基于同步加速器的元素特定的X射线衍射（XRD）和X射线磁圆二色性（XMCD）比较粉末和薄膜的属性的自发霍尔效应在膜中的本地化的Ir时刻。我们链接的薄膜Ir本地矩晶格畸变中不存在的散装粉末。我们的结论是，高温自发霍尔效应是由拓扑效应起源于无论是从Ir或Pr亚晶格，与相互作用强度增强的Ir本地矩。这种具有弱净矩的自发霍尔效应突出了作为发现金属受抑磁性材料中拓扑现象的一种手段的极小晶格畸变的效果。
Rare earth pyrochlore Iridates (RE2Ir2O7) consist of two interpenetrating cation sublattices, the RE with highly-frustrated magnetic moments, and the Iridium with extended conduction orbitals significantly mixed by spin-orbit interactions. The coexistence and coupling of these two sublattices create a landscape for discovery and manipulation of quantum phenomena such as the topological Hall effect, massless conduction bands, and quantum criticality. Thin films allow extended control of the material system via symmetry-lowering effects such as strain. While bulk Pr2Ir2O7 shows a spontaneous hysteretic Hall effect below 1.5K, we observe the effect at elevated temperatures up to 15K in epitaxial thin films on (111) YSZ substrates synthesized via solid phase epitaxy. Similar to the bulk, the lack of observable long-range magnetic order in the thin films points to a topological origin. We use synchrotron-based element-specific x-ray diffraction (XRD) and x-ray magnetic circular dichroism (XMCD) to compare powders and thin films to attribute the spontaneous Hall effect in the films to localization of the Ir moments. We link the thin film Ir local moments to lattice distortions absent in the bulk-like powders. We conclude that the elevated-temperature spontaneous Hall effect is caused by the topological effect originating either from the Ir or Pr sublattice, with interaction strength enhanced by the Ir local moments. This spontaneous Hall effect with weak net moment highlights the effect of vanishingly small lattice distortions as a means to discover topological phenomena in metallic frustrated magnetic materials.