Variable magnetic interactions in an organic radical system of (m-N-methylpyridinium α-nitronyl nitroxide)⋅<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msup><mml:mrow><mml:mi mathvariant="italic">X</mml:mi></mml:mrow><mml:mrow><mml:mi mathvariant="normal">−</mml:mi></mml:mrow></mml:msup></mml:mrow></mml:math>: A possiblekagoméantiferromagnet

Awaga, Kunio; Okuno, Tsunehisa; Yamaguchi, Akira; Hasegawa, Masamitsu; Inabe, Tamotsu; Maruyama, Yusei; Wada, Nobuo

doi:10.1103/physrevb.49.3975

Cited by 149 publications

(81 citation statements)

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“…As a real material, Wada and coworkers 11,12,13) have investigated the magnetic behavior of m-MPYNN·BF 4 which can be regarded as the S = 1 kagomé antiferromagnet. * e-mail: hida@phy.saitama-u.ac.jp This material, however, undergoes a structual transformation at 128.7K to the distorted phase with √ 3 × √ 3 structure.…”

Section: )mentioning

confidence: 99%

Magnetization Process of theS=1 and 1/2 Uniform and Distorted Kagomé Heisenberg Antiferromagnets

2001

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The magnetization process of the S = 1 and 1/2 kagomé Heisenberg antiferromagnet is studied by means of the numerical exact diagonalization method. It is found that the magnetization curve at zero temperature has a plateau at 1/3 of the full magnetization. In the presence of √ 3 × √ 3 lattice distortion, this plateau is enhanced and eventually the ferrimagnetic state is realized. There also appear the minor plateaux above the main plateau. The physical origin of these phenomena is discussed.KEYWORDS: kagomé Heisenberg antiferromagnet, numerical diagonalization, magnetization plateau §1. IntroductionThe kagomé Heisenberg antiferromagnet (KHAF) has been extensively studied theoretically and experimentally because of the interest in the interplay of the strong quantum fluctuation and the highly frustrated nature of the lattice structure. So far, most of the attempts have been focused on the ground state and low lying excitations of the uniform KHAF. In both S = 1/2 1, 2, 3, 4) and S = 1 5) cases, it is known that the ground state is a spin singlet state and the magnetic excitation has a finite energy gap. In the S = 1/2 case, there are a number of singlet excitations below the first triplet excitation possiblly down to zero energy in the thermodynamic limit. 4)On the other hand, the singlet excitations also have finite energy gaps in the S = 1 case. The present author proposed the hexagonal singlet solid (HSS) picture for the ground state of S = 1 KHAF. 5)In the present work, we first investigate the magnetization process of this model. As examples of the frustrated quantum magnets, the magnetization process of the triangular Heisenberg magnet is widely studied. 6, 8, 7)The magnetization plateau at one-third of the full magnetization is well estabilshed in the Ising-like classical Heisenberg model as a typical example of the 'classical' magnetization plateau. 7) Although this plateau can be well understood in terms of the classical spin configuration, it has been observed even in the isotropic Heisenberg model with S = 1/2 which has strong quantum fluctuation.8) On the other hand, the honeycomb lattice S = 1/2 Heisenberg antiferromagnet has no plateau. 8)In this context, it is interesting to investigate the case of kagomé lattice which has the triangles and hexagons at the same time.As a real material, Wada and coworkers 11,12,13) have investigated the magnetic behavior of m-MPYNN·BF 4 which can be regarded as the S = 1 kagomé antiferromagnet. * e-mail: hida@phy.saitama-u.ac.jp This material, however, undergoes a structual transformation at 128.7K to the distorted phase with √ 3 × √ 3 structure.14) Motivated by this observation, we further investigate the effect of such lattice distortion to the ground state and magnetization process in both S = 1/2 and S = 1 cases. We find that the plateau is enhanced by the lattice distortion and eventually the ferrimagnetic ground state is realized. This paper is organized as follows: In §2, the model Hamiltonian is presented. The numerical results for the magnetization curves a...

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Section: )mentioning

confidence: 99%

Magnetization Process of theS=1 and 1/2 Uniform and Distorted Kagomé Heisenberg Antiferromagnets

2001

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“…Numerical studies on the KHAF models with spin magnitude up to S = 3 showed that, 3 while long-range magnetic order appears for S ≥ 3/2, the ground states for the S = 1/2 and S = 1 KHAF models remain non-magnetic. Experimentally, a number of spin-1 kagome compounds have been synthesized and analyzed, e.g., m-MPYNN·BF 4 [4][5][6][7] and Ni 3 V 2 O 8 8 . The former has been found to be nonmagnetic even at very low temperatures (30mK), 5 and a spin gap has also been observed.…”

Section: Introductionmentioning

confidence: 99%

Hexagon-singlet solid ansatz for the spin-1 kagome antiferromagnet

Weichselbaum

Delft

et al. 2015

Phys. Rev. B

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We perform a systematic investigation on the hexagon-singlet solid (HSS) states, which are a class of spin liquid candidates for the spin-1 kagome antiferromagnet. With the Schwinger boson representation, we show that all HSS states have exponentially decaying correlations and can be interpreted as a (special) subset of the resonating Affleck-Kennedy-Lieb-Tasaki (AKLT) loop states. We provide a compact tensor network representation of the HSS states, with which we are able to calculate physical observables efficiently. We find that the HSS states have vanishing topological entanglement entropy, suggesting the absence of intrinsic topological order. We also employ the HSS states to perform a variational study of the spin-1 kagome Heisenberg antiferromagnetic model. When we use a restricted HSS ansatz preserving lattice symmetry, the best variational energy per site is found to be e0 = −1.3600. In contrast, when allowing lattice symmetry breaking, we find a trimerized simplex valence bond crystal with a lower energy, e0 = −1.3871.

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“…In this search for new kagome compounds, oxalate ligands have little been exploited, although they are known to stabilize rather strong magnetic interactions, and have been used previously in the synthesis of honeycomb systems [9], which are potentially frustrated beyond NN interactions. Recently, new molecular kagome compounds with other ligands have been synthesized [10,11,12]. Due to the small value of the spins involved, they are all considered as realizations of a quantum kagome lattice.…”

Section: Introductionmentioning

confidence: 99%

Magnetic properties of a family of quinternary oxalates

et al. 2013

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Abstract. We report on the magnetic properties of four isomorphous compounds of a family of quinternary oxalates down to 60 mK. In all these materials, the magnetic Fe II ions with a strong magneto-crystalline anisotropy form a distorted kagome lattice, topologically equivalent to a perfect kagome one if nearestneighbor interactions only are considered. All the compounds order at low temperature in an antiferromagnetic arrangement with magnetic moments at 120• . A remarkable magnetic behavior emerges below the Néel temperature in three compounds (with inter-kagome-layer Zr, Sn, Fe but not with Al): the spin anisotropy combined with a low exchange path network connectivity lead to domain walls intersecting the kagome planes through strings of free spins. These produce an unfamiliar slow spin dynamics in the ordered phase observed by AC susceptibility, evolving from exchange-released spin-flips towards a cooperative behavior on decreasing the temperature.PACS. 75.25.-j Spin arrangements in magnetically ordered materials -75.60.Ch Domain walls and domain structure -75.40.Gb Dynamic properties -75.50.Ee Antiferromagnetics

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Variable magnetic interactions in an organic radical system of (m-N-methylpyridinium α-nitronyl nitroxide)⋅X−: A possiblekagoméantiferromagnet

Cited by 149 publications

References 14 publications

Magnetization Process of theS=1 and 1/2 Uniform and Distorted Kagomé Heisenberg Antiferromagnets

Magnetization Process of theS=1 and 1/2 Uniform and Distorted Kagomé Heisenberg Antiferromagnets

Hexagon-singlet solid ansatz for the spin-1 kagome antiferromagnet

Magnetic properties of a family of quinternary oxalates

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