title: An orbital-selective spin liquid in a frustrated heavy fermion spinel LiV₂O₄.
abstract: 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.
authors.affiliation: Department of Physics, Graduate School of Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8602, Japan. yasuhiro@iar.nagoya-u.ac.jp
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Shimizu
authors.forename: Hikaru
authors.initials: H
authors.lastname: Takeda
authors.forename: Moe
authors.initials: M
authors.lastname: Tanaka
authors.forename: Masayuki
authors.initials: M
authors.lastname: Itoh
authors.forename: Seiji
authors.initials: S
authors.lastname: Niitaka
authors.forename: Hidenori
authors.initials: H
authors.lastname: Takagi