Pr₂Ir₂O₇中的稀土自旋纹理及电子非均匀性的形成路径
Rare-earth spin textures and a route to electronic inhomogeneity in $Pr_2Ir_2O_7$
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中文总结 AI 辅助
本研究针对Pr₂Ir₂O₇低温下的电子非均匀性问题，通过蒙特卡洛模拟结合Hartree-Fock模型，揭示了受挫的Pr自旋纹理是引发近藤屏蔽与破坏区非均匀混合的关键因素。
中文摘要 AI 辅助
烧绿石铱化物Pr₂Ir₂O₇在低温下仍保持金属性，而其同系物则为绝缘体。近期扫描隧道谱实验发现，室温解理该材料表面时，会呈现近藤屏蔽区与近藤破坏区的非均匀混合态，而低温解理时表面则保持均匀性。本研究探究是否是受挫的镨自旋纹理引发了这种非均匀性。为此，研究人员生成蒙特卡洛采样的Pr自旋冰构型（推测其随时间演化缓慢），并通过局域近藤交换作用J_K与Ir电子的八带Hartree-Fock模型耦合。研究进一步发现，同系物常见的全进全出态的电荷间隙会随耦合J_K平滑闭合，而近期提出的富含单极子的“水母”纹理会使绝缘行为进一步被抑制，ΔJ_{Kc}≈0.03 t。此外，在大尺寸Pr表面扫描小团簇可得到合成隧穿图谱，该图谱会碎裂为海洋中的岛状结构。尽管本经典可模拟理论未包含近藤单态，但其产生的费米能级态密度的空间调制，通过近藤温度的指数Doniach敏感性，足以打破局域屏蔽与磁有序之间的平衡，为观测到的近藤/近藤破坏非均匀性提供了一条由受挫驱动的路径。
英文摘要
The pyrochlore iridate $Pr_2Ir_2O_7$ remains metallic at low temperatures where its family members insulate. Recently, scanning tunneling spectroscopy experiments have revealed an inhomogeneous mixture of Kondo-screened and Kondo-destroyed regions when its surface is produced by cleaving at room temperature while it remains uniform when cleaved at low temperatures. We ask whether the frustrated praseodymium spin texture seeds this inhomogeneity. To study this, we produce Monte-Carlo-sampled Pr spin-ice configurations, presumed to evolve slowly in time, and couple through a local Kondo exchange $J_K$ to an eight-band Hartree-Fock model of the Ir electrons. We further find the charge gap of the all-in-all-out state common in the other family members closes smoothly with the coupling $J_K$, and the recently proposed monopole-rich ``jellyfish'' textures further suppress the insulating behavior by $ΔJ_{Kc}\approx 0.03\,t$. Additionally, scanning a small cluster across a large Pr surface yields a synthetic tunneling map that fractures into islands within a sea. Although our classical simulable theory omits the Kondo singlet, the spatial modulation of the Fermi-level density of states it produces is, through the exponential Doniach sensitivity of the Kondo temperature, sufficient to tip the local balance between screening and magnetic order; a frustration-driven route to the observed Kondo/Kondo-destroyed inhomogeneity.
