Discrete antiferromagnetic spin-wave excitations in the giant ferric wheel Fe<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msub><mml:mrow /><mml:mn>18</mml:mn></mml:msub></mml:math>

Ummethum, Jörg; Nehrkorn, Joscha; Mukherjee, Shreya; Ivanov, N. B.; Stuiber, S.; Strässle, Th.; Tregenna‐Piggott, Philip L. W.; Mutka, H.; Christou, George; Waldmann, Oliver; Schnack, Jürgen

doi:10.1103/physrevb.86.104403

Cited by 41 publications

(31 citation statements)

References 66 publications

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“…The H AB model has been very successfully applied to even-membered antiferromagnetic Heisenberg rings (odd-membered rings will not be considered in this work), 31 and experimentally confirmed in fine detail for the Cr 8 , CsFe 8 , and Fe 18 molecular wheels. [32][33][34] Further examples are the Mn- [3 × 3] grid and the Fe 30 Keplerate molecules. [35][36][37][38][39] For short chains with open ends, however, the E(S) ∝ S(S + 1) approximation of the L band appears to work very well for odd chains, while for even chains it surprisingly fails in the low-energy sector.…”

Section: Introductionmentioning

confidence: 99%

Even-odd effect in short antiferromagnetic Heisenberg chains

et al. 2013

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Motivated by recent experiments on chemically synthesized magnetic molecular chains, we investigate the lowest-lying energy band of short spin-s antiferromagnetic Heisenberg chains focusing on effects of open boundaries. By numerical diagonalization we find that the Landé pattern in the energy levels, i.e., E(S) ∝ S(S + 1) for total spin S, known from, e.g., ring-shaped nanomagnets, can be recovered in odd-membered chains, while strong deviations are found for the lowest excitations in chains with an even number of sites. This particular even-odd effect in the short Heisenberg chains cannot be explained by simple effective Hamiltonians and symmetry arguments. We go beyond these approaches, taking into account quantum fluctuations by means of a path-integral description and the valence bond basis, but the resulting quantum edge-spin picture which is known to work well for long chains does not agree with the numerical results for short chains and cannot explain the even-odd effect. Instead, by analyzing also the classical chain model, we show that spatial fluctuations dominate the physical behavior in short chains, with length N e πs , for any spin s. Such short chains are found to display a unique behavior, which is not related to the thermodynamic limit and cannot be described well by theories developed for this regime.

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Section: Introductionmentioning

confidence: 99%

Even-odd effect in short antiferromagnetic Heisenberg chains

et al. 2013

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“…INS has been shown to be a powerful technique for understanding magnetic behavior in molecular magnets [6,7], including compounds with large Hilbert space such as an Fe 18 ring [8]. In this paper, we use low-temperature INS measurements and the Lanczos diagonalization method [9] to help clarify the question of the actual coupling between the {Fe 6 } and {Fe 3 } fragments, as well as to determine more realistic values of all of the exchange constants.…”

Section: Introductionmentioning

confidence: 99%

Refined model of the {Fe9} magnetic molecule from low-temperature inelastic neutron scattering studies

et al. 2014

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We present a refined model of the {Fe 9 } tridiminished icosahedron magnetic molecule system. This molecule was originally modeled as being composed of two ({Fe 3 } and {Fe 6 }) clusters, with the Fe 3+ ions within each cluster being coupled via exchange interactions, but with no coupling between the clusters. The present inelastic neutron scattering (INS) measurements were used to probe the low-lying energy spectrum of {Fe 9 }, and these results demonstrate that the previously published model of two uncoupled clusters is incomplete. To achieve agreement between the experiment and theory, we have augmented the model with relatively small exchange coupling between the clusters. A combination of Lanczos matrix diagonalization and quantum Monte Carlo simulations have been used to achieve good agreement between the experimental data and the improved model of the full {Fe 9 } system despite the complexity of this model (with Hilbert space dimension >10 7 ).

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“…Most of the results in this section are obtained through DMRG simulations by performing seven sweeps and keeping up to 500 states in the last sweep [10,11,12]. This ensures a good convergence with a discarded weight of the order of 10 −8 or better.…”

Section: Quantum Phase Diagrammentioning

confidence: 99%

Alternating-spin S = 3/2 and σ = 1/2 Heisenberg chain with isotropic three-body exchange interactions

2016

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Abstract. The promotion of collinear classical spin configurations as well as the enhanced tendency towards nearest-neighbor clustering of the quantum spins are typical features of the frustrating isotropic three-body exchange interactions in Heisenberg spin systems. Based on numerical density-matrix renormalization group calculations, we demonstrate that these extra interactions in the Heisenberg chain constructed from alternating S = 3/2 and σ = 1 2 site spins can generate numerous specific quantum spin states, including some partially-polarized ferrimagnetic states as well as a doubly-degenerate non-magnetic gapped phase. In the non-magnetic region of the phase diagram, the model describes a crossover between the spin-1 and spin-2 Haldane-type states.PACS. 75.10.Jm Quantized spin models -75.40.Mg Numerical simulation studies -75.45.+j Macroscopic quantum phenomena in magnetic systems

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Discrete antiferromagnetic spin-wave excitations in the giant ferric wheel Fe18

Cited by 41 publications

References 66 publications

Even-odd effect in short antiferromagnetic Heisenberg chains

Even-odd effect in short antiferromagnetic Heisenberg chains

Refined model of the {Fe9} magnetic molecule from low-temperature inelastic neutron scattering studies

Alternating-spin S = 3/2 and σ = 1/2 Heisenberg chain with isotropic three-body exchange interactions

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