Frustration- and doping-induced magnetism in a Fermi–Hubbard simulator
Frustration- and doping-induced magnetism in a Fermi–Hubbard simulator
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DOI：
10.1038/s41586-023-06280-5
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发表时间：
2022-12
期刊：
影响因子：
64.8
通讯作者：
Muqing Xu;L. Kendrick;Anant Kale;You-Na Gang;G. Ji;R. Scalettar;M. Lebrat;M. Greiner
中科院分区：
文献类型：
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作者：
Muqing Xu;L. Kendrick;Anant Kale;You-Na Gang;G. Ji;R. Scalettar;M. Lebrat;M. Greiner
强关联系统中的几何挫折可以产生过多的新的有序状态和有趣的磁相，如量子自旋液体，-。有前途的候选材料，这样的阶段，-可以描述的哈伯德模型的各向异性三角形晶格，一个范式模型捕捉强相关性和磁挫折之间的相互作用，-。然而，在巡回掺杂剂的存在下，受抑磁性的命运仍然不清楚，以及它与正方形哈伯德模型的掺杂相的联系。在这里，我们调查的局部自旋序的哈伯德模型与可控挫折和掺杂，使用超冷费米子在各向异性光学晶格连续可调从正方形到三角形的几何形状。在半填充和强相互作用下，我们在单点水平上观察到挫折如何减少磁相关的范围，并驱动从共线Néel反铁磁体到短程相关120°螺旋相位的转变。远离半填充，三角形的限制显示增强的反铁磁相关性的空穴掺杂侧和铁磁相关性的逆转，在粒子掺杂超过20%，暗示在受挫系统中的作用的动力学磁性。这项工作为探索三角晶格中可能的手性有序或超导相铺平了道路，并实现了t-t ′方晶格Hubbard模型，这可能是描述铜酸盐材料超导性所必需的。
Geometrical frustration in strongly correlated systems can give rise to a plethora of novel ordered states and intriguing magnetic phases, such as quantum spin liquids, –. Promising candidate materials for such phases, –can be described by the Hubbard model on an anisotropic triangular lattice, a paradigmatic model capturing the interplay between strong correlations and magnetic frustration, , , –. However, the fate of frustrated magnetism in the presence of itinerant dopants remains unclear, as well as its connection to the doped phases of the square Hubbard model. Here we investigate the local spin order of a Hubbard model with controllable frustration and doping, using ultracold fermions in anisotropic optical lattices continuously tunable from a square to a triangular geometry. At half-filling and strong interactionsU/t≈ 9, we observe at the single-site level how frustration reduces the range of magnetic correlations and drives a transition from a collinear Néel antiferromagnet to a short-range correlated 120° spiral phase. Away from half-filling, the triangular limit shows enhanced antiferromagnetic correlations on the hole-doped side and a reversal to ferromagnetic correlations at particle dopings above 20%, hinting at the role of kinetic magnetism in frustrated systems. This work paves the way towards exploring possible chiral ordered or superconducting phases in triangular lattices,and realizingt–t′ square lattice Hubbard models that may be essential to describe superconductivity in cuprate materials.