One-ninth magnetization plateau stabilized by spin entanglement in a kagome antiferromagnet

The spin-1/2 antiferromagnetic Heisenberg model on a Kagome lattice is geometrically frustrated, which is expected to promote the formation of many-body quantum entangled states. The most sought-after among these is the quantum spin liquid phase, but magnetic analogs of liquid, solid, and supersolid phases may also occur, producing fractional plateaus in the magnetization. Here, we investigate the experimental realization of these predicted phases in the Kagome material YCu3(OD)6+xBr3-x (x=0.5). By combining thermodynamic and Raman spectroscopic techniques, we provide evidence for fractionalized spinon excitations and observe the emergence of a 1/9 magnetization plateau. These observations establish YCu3(OD)6+xBr3-x as a model material for exploring the 1/9 plateau phase.Comment: to appear in Nature Physics, 33 pagses, 15 figure

Simulation-based planning system for shipbuilding

To maintain the competitiveness of shipyards in the current, difficult situation, further improvements to technology are necessary. Recently, various production technologies have been developed to advance the shipyard production environment under the influence of the Industry 4.0 toward automation, smart factories, and intelligent planning systems. To contribute to such efforts, we introduce a research case aimed at a simulation-based shipbuilding planning system. Shipbuilding planning processes are reorganized using an integrated planning and scheduling system, and a process-centric discrete event system simulation is used to enhance planning quality. Moreover, the proposed simulation-based planning system is applied to an actual shipbuilding process, proving that it could enhance the quality of production planning through several productivity evaluation indices.Y

Random-singlet-like state emergent in s = 5/2 frustrated cubic lattice

We employ thermodynamic and electron spin resonance (ESR) techniques to elucidate the effects of quenched disorder on a ground state of s= 5 / 2 frustrated cubic antiferromagnet La 3 Sb 3 Mn 2 O 14 . We observe the development of multiple ESR lines for temperatures below 80 K. Concomitantly, the ESR linewidth exhibits a power-law increase, accompanied by an intriguing shift in resonance fields. These observations point to the occurrence of inhomogeneous magnetism. Additionally, ac magnetic susceptibility and magnetization data obey a scaling relation of χ′(H, T) and M(H, T) in μBH/ kBT with the scaling exponent α= 0.53 . This scaling behavior alludes to the formation of a random-singlet-like state and the presence of abundant low-lying excitations. Our results highlight the concerted interplay of strong disorder and frustration to stabilize a putative random-singlet state even in classical and high-dimensional spin systems. © 2024, The Korean Physical Society.11Nscopuskc

Partial molecular orbitals in face-sharing 3d manganese trimer: Comparative studies on Ba_{4}TaMn_{3}O_{12} and Ba_{4}NbMn_{3}O_{12}

We present a molecular orbital candidate Ba_{4}TaMn_{3}O_{12} with a face-sharing octahedra trimer, by comparing it with a related compound Ba_{4}NbMn_{3}O_{12}. The synthesis of the polycrystalline powder is optimized by suppressing the secondary impurity phase via x-ray diffraction. Magnetic susceptibility measurements on the optimized samples reveal a weak magnetic hysteresis with magnetic transitions consistent with heat capacity results. The effective magnetic moments from susceptibility indicate a strongly coupled S=2 antiferromagnetic trimer at around room temperature, whereas the estimated magnetic entropy from heat capacity suggests the localized S=3/2 timer. These results can be explainable by a partial molecular orbital state, in which three t_{2g} electrons are localized in each Mn ion and one e_{g} electron is delocalized over two-end Mn ions of the trimer based on density functional theory calculations. This unconventional 3d orbital state is comprehended as a consequence of competition between the hybrid interatomic orbitals within the Mn trimer and the local moment formation by on-site Coulomb correlations

Spin dynamics of the one-dimensional double chain spin- 12 antiferromagnet KNaCuP2 O7

© 2022 American Physical Society.We combine a muon spin relaxation (μSR) technique with thermodynamic measurements to explore the spin dynamics of one-dimensional (1D) S=12 antiferromagnetic double chain KNaCuP2O7. Static magnetic susceptibility and specific heat are well described by a uniform 1D spin chain model with the intrachain interaction J/kB≈55K and small interchain interactions. Spin excitations probed by zero-field μSR evince that high-temperature diffusive spin transport turns into ballistic behavior with decreasing temperature below 30 K. In addition, we observe that longitudinal-field μSR varies hardly with an external magnetic field. The field-independent dynamical spin susceptibility disagrees with diffusive or ballistic behaviors.11Nsciescopu

Li₆M(SeO₃)₄ (M = Co, Ni, and Cd) and Li₂Zn(SeO₃)₂: Selenites with Late Transition-Metal Cations

A series of lithium metal selenites, Li₆M­(SeO₃)₄ (M = Co, Ni, and Cd) and Li₂Zn­(SeO₃)₂, were synthesized by hydrothermal and solid-state reactions. Li₆M­(SeO₃)₄ is composed of Li⁺ cations, MO₆ octahedra, and SeO₃ polyhedra, while Li₂Zn­(SeO₃)₂ consists of Li⁺, Zn­(Li)­O₄ tetrahedra, and SeO₃ polyhedra. Isostructural Li₆Co­(SeO₃)₄ and Li₆Ni­(SeO₃)₄ crystallize in the rhombohedral space group <i>R</i>3̅, forming a three-dimensional distorted cubic lattice. Li₂Zn­(SeO₃)₂ crystallizes in the orthorhombic space group <i>Pbam</i> and reveals a layered structure in the <i>bc</i> plane. Li₆Cd­(SeO₃)₄ revealing a unidimensional structure crystallizes in the polar non-centrosymmetric space group <i>C</i>2, attributed to the parallel alignment of distorted CdO₆ octahedra. The direct-current magnetic susceptibility measurements unveil that Li₆Co­(SeO₃)₄ is a canted antiferromagnet with <i>T</i>_N = 25 K, while Li₆Ni­(SeO₃)₄ undergoes an antiferromagnetic transition at <i>T</i>_N = 54 K, having a negligible canted moment. The weak ferromagnetism observed in Li₆Co­(SeO₃)₄ indicates the significance of spin–orbit coupling, bringing about anisotropic exchange interactions. Li₆Cd­(SeO₃)₄ reveals a second harmonic generation (SHG) efficiency of 10 × α-SiO₂. Dipole moment calculations on Li₆Cd­(SeO₃)₄ indicate that the cooperative interaction of CdO₆ and SeO₃ is responsible for the observed SHG properties. Band gaps of the compounds are enlarged as atomic number increases. The effect of late transition-metal cations with different coordination numbers on the framework structures and the subsequent physical properties will be also discussed

Coexistence of random singlets and disordered Kitaev spin liquid in H3LiIr2O6

©2023 American Physical Society. We combine static magnetic susceptibility chi(T), muon-spin relaxation, and H-1 nuclear magnetic resonance measurements to explore the spin dynamics in the disordered-induced quantum spin liquid candidate H3LiIr2O6. Inverse Laplace transform analysis of the H-1 spin-lattice relaxation rate 1/T-1 enables us to identify two characteristic temperatures Tg = 110 K and T* = 26 K. Below T-g, a slower 1/T-1(slow) component dictated by gapped excitations with a spin gap Delta(h) = 30-38 K evolves distinctly from a faster 1/T-1(fast) component pertaining to gapless excitations. Furthermore, we observe a sub-Curie divergent chi(T) proportional to T-0.68, a power-law dependent 1/T fast 1 proportional to T 1.4, and a weakly activated 1/(slow)(T) 1 proportional to exp(-Delta(l)/k(B)T) (Delta(l) = 3-6 K) below T* = 26 K. All these features suggest the coexistence of a disordered spin-liquid state and spin singlets with spatially distributed gaps.11Nsciescopu

Kondo screening in a Majorana metal

Kondo impurities provide a nontrivial probe to unravel the character of the excitations of a quantum spin liquid. In the S = 1/2 Kitaev model on the honeycomb lattice, Kondo impurities embedded in the spin-liquid host can be screened by itinerant Majorana fermions via gauge-flux binding. Here, we report experimental signatures of metallic-like Kondo screening at intermediate temperatures in the Kitaev honeycomb material α-RuCl3 with dilute Cr3+ (S = 3/2) impurities. The static magnetic susceptibility, the muon Knight shift, and the muon spin-relaxation rate all feature logarithmic divergences, a hallmark of a metallic Kondo effect. Concurrently, the linear coefficient of the magnetic specific heat is large in the same temperature regime, indicating the presence of a host Majorana metal. This observation opens new avenues for exploring uncharted Kondo physics in insulating quantum magnets. © 2023, The Author(s).11Ysciescopu

Open-Framework Iron Fluoride Phosphates Based on Chain, Trinuclear, and Tetranuclear Chain FeIIIBuilding Units: Crystal Structures and Magnetic Properties

Copyright © 2022 American Chemical Society. We report the synthesis and characterization of a series of new open-framework iron fluoride-fluorophosphates based on linear, trinuclear, and tetranuclear chain FeIII building units. KFe2(PO3F)2F3 (I) consists of {Fe2(O3F)2F2}10- zigzag chains interconnected by P(O/F)4 tetrahedra forming a three-dimensional (3D) open framework. K2Fe(PO2.5F1.5)2F2 (II) is built up by {Fe(PO2.5F1.5)2F2}2- chains separated by K+ cation layers. The framework for K3Fe3(PO4)(PO3F)2F5 (III) contains two-dimensional {Fe3O4F4(PO3F)2}2- sheets, which are built from trimeric Fe-octahedra insulated by PO3F tetrahedra. The macroanionic framework of K3Fe4(PO4)2F9 (IV) comprises linear {Fe4O8F9}10- chains consisting of tetranuclear magnetic clusters of [Fe4O8F9]10- formed via corner-sharing fluorine atoms decorated with PO4 groups. The magnetic characterization of three iron fluorophosphates reveals diversified magnetism: S = 5/2 spin chains for I, antiferromagnetically coupled triangular Fe units for III, and coupled tetrahedral S = 5/2 spin chains for IV. IV shows strong geometric frustration thanks to its spin motifs of corner-shared tetrahedral clusters. © 2022 American Chemical Society.11Nsciescopu

Timescale distributions of spin fluctuations in the S=2 kagome antiferromagnet CsMn3 F6 (SeO3)2

© 2022 American Physical Society.We report the static and dynamical properties of a newly discovered S=2 kagome antiferromagnet CsMn3F6(SeO3)2. By combining dc and ac magnetic susceptibilities, specific heat, electron spin resonance (ESR), and muon spin relaxation (μSR), we identify two characteristic temperatures T∗=8 K and T=|ΘCW|=49(1) K, thereby three distinct regimes: a paramagnetic, a cooperative paramagnetic, and a quasistatic ordered state. At high temperature (T>|ΘCW|), the ac susceptibility and ESR linewidth show a power-law dependence, reflecting short-range spin-spin correlations of the paramagnetic Mn3+ ions. In the cooperative paramagnetic regime (T∗<T<|ΘCW|), the ESR signals evince the development of dichotomic spin correlations, which is interpreted in terms of the distinct timescales of in-plane and out-of-plane spin fluctuations. Remarkably, we observe a broad maximum at the characteristic temperature scale of Tcl=20 K (≈|Jcl|) in the specific heat and ESR results, suggesting short-range ordering. At low temperatures below T∗, the μSR data suggest the presence of dynamically fluctuating fields with partially frozen moments, consistent with the absence of long-range order evidenced by specific heat and magnetic susceptibility data. A magnetic behavior that depends on the chosen time window points to the presence of multiple timescales and temporally anisotropic spin correlations, as predicted for a classical kagome antiferromagnet.11Nsciescopu