Department of Physics, Graduate School of Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8602, Japan.
Nat Commun. 2012;3:981. doi: 10.1038/ncomms1979.
The pronounced enhancement of the effective mass is the primary phenomenon associated with strongly correlated electrons. In the presence of local moments, the large effective mass is thought to arise from Kondo coupling, the interaction between itinerant and localized electrons. However, in d electron systems, the origin is not clear because of the competing Hund's rule coupling. Here we experimentally address the microscopic origin for the heaviest d fermion in a vanadium spinel LiV(2)O(4) having geometrical frustration. Utilizing orbital-selective (51)V NMR, we elucidate the orbital-dependent local moment that exhibits no long-range magnetic order despite persistent antiferromagnetic correlations. A frustrated spin liquid, Hund-coupled to itinerant electrons, has a crucial role in forming heavy fermions with large residual entropy. Our method is important for the microscopic observation of the orbital-selective localization in a wide range of materials including iron pnictides, cobaltates, manganites and ruthnates.
强烈关联电子的主要现象是有效质量的明显增强。在存在局域矩的情况下，大的有效质量被认为是由 Kondo 耦合引起的，即巡游电子和局域电子之间的相互作用。然而，在 d 电子体系中，由于竞争的 Hund 规则耦合，其起源尚不清楚。在这里，我们通过实验解决了具有几何各向异性的尖晶石 LiV(2)O(4)中最重的 d 费米子的微观起源问题。利用轨道选择的 (51)V NMR，我们阐明了轨道依赖的局域矩，尽管存在持久的反铁磁关联，但它没有长程磁有序。一个与巡游电子 Hund 耦合的各向异性自旋液体在形成具有大剩余熵的重费米子方面起着至关重要的作用。我们的方法对于在包括铁磷化物、钴酸盐、锰氧化物和 ruthnates 在内的广泛材料中进行轨道选择局域化的微观观察非常重要。
