Magnetic resonance in quantum spin chains

Nidda, H.-A. Krug von; Büttgen, N.; Loidl, A.

doi:10.1140/epjst/e2010-01217-0

Cited by 9 publications

(13 citation statements)

References 119 publications

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“…In both cases we observe an increase of the resonance shift δ ω and a broadening of the spectral lines, measured as an increase of ∆ω, for decreasing temperatures. This is interesting as it seems to contradict experimental results 4 which claim a narrowing. This discrepancy is due to the different measures for the line width here and in the experimental literature.…”

Section: A Field-dependent Momentsmentioning

confidence: 71%

Absorption of microwaves by the one-dimensional spin-12Heisenberg-Ising magnet

Brockmann

Göhmann²,

Karbach³

et al. 2012

Phys. Rev. B

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We analyze the absorption of microwaves by the Heisenberg-Ising chain combining exact calculations, based on the integrability of the model, with numerical calculations. Within linear response theory the absorbed intensity is determined by the imaginary part of the dynamical susceptibility. The moments of the normalized intensity can be used to define the shift of the resonance frequency induced by the interactions and the line width independently of the shape of the spectral line. These moments can be calculated exactly as functions of temperature and strength of an external magnetic field, as long as the field is directed along the symmetry axis of the chain. This allows us to discuss the line width and the resonance shift for a given magnetic field in the full range of possible anisotropy parameters. For the interpretation of these data we need a qualitative knowledge of the line shape which we obtain from fully numerical calculations for finite chains. Exact analytical results on the line shape are out of reach of current theories. From our numerical work we could extract, however, an empirical parameter-free model of the line shape at high temperatures which is extremely accurate over a wide range of anisotropy parameters and is exact at the free fermion point and at the isotropic point. Another prediction of the line shape can be made in the zero-temperature and zero magnetic field limit, where the sufficiently anisotropic model shows strong absorption. For anisotropy parameters in the massive phase we derive the exact two-spinon contribution to the spectral line. From the intensity sum rule it can be estimated that this contribution accounts for more than 80% of the spectral weight if the anisotropy parameter is moderately above its value at the isotropic point.

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Section: A Field-dependent Momentsmentioning

confidence: 71%

Absorption of microwaves by the one-dimensional spin-12Heisenberg-Ising magnet

Brockmann

Göhmann²,

Karbach³

et al. 2012

Phys. Rev. B

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“…The latter are usually organic compounds (see, for instance, Refs. [11,12]), the only well-established inorganic spin-Peierls material up to now being CuGeO 3 (see, e.g., Ref. [13]).…”

Section: Introductionmentioning

confidence: 99%

Coherent spin dynamics of solitons in the organic spin chain compounds(o-DMTTF)2X(X=Cl,Br)

et al. 2019

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We studied the magnetic properties, in particular dynamics, of the correlated spins associated with natural defects in the organic spin chain compounds (o -DMTTF)2X (X = Br, Cl) by means of electron spin resonance (ESR) spectroscopy. Both materials exhibit spin-Peierls transitions at temperatures around 50 K [Foury-Leylekian et al., Phys. Rev. B 84, 195134 (2011)], which allow a separation of the properties of defects inside the chains from the magnetic response of the spin chains. Indeed, continuous wave ESR measurements performed over a wide temperature range evidence the evolution of the spin dynamics from being governed by the spins in the chains at elevated temperatures to a low-temperature regime which is dominated by defects within the spindimerized chains. In addition, contributions of triplon excitations to the ESR response below the transition temperature were observed which provides a spectroscopic estimate for the spin-gap of the studied systems. Moreover, details of spin dynamics deep in the spin-Peierls phase were investigated by pulse ESR experiments which revealed Rabi-oscillations as signatures of coherent spin dynamics. We discuss the results obtained from these complementary methods of ESR spectroscopy in terms of solitons localized at the defect sites within the chains. From a comparison of the characteristic damping times of the Rabi oscillations with measurements of the spin relaxation times by means of primary-echo decay and CPMG methods it becomes evident that inhomogeneities in local magnetic fields strongly contribute to the soliton decoherence.

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“…At first sight this seems to contradict experimental results [4] which claim a narrowing. Still, one has to take into account that usually in the analysis of experimental data rather different definitions of the line width, as e.g.…”

mentioning

confidence: 68%

“…Of particular interest are experiments on quasi one-dimensional compounds (reviewed e.g. in [3,4]) which provide prototypical realizations of interacting many-body systems with strong quantum fluctuations. Still, the data are not always easy to interpret, because of a lack of reliable theoretical predictions.…”

mentioning

confidence: 99%

Theory of Microwave Absorption by the Spin-1/2Heisenberg-Ising Magnet

Brockmann

Göhmann²,

Karbach³

et al. 2011

Phys. Rev. Lett.

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We analyze the problem of microwave absorption by the Heisenberg-Ising magnet in terms of shifted moments of the imaginary part of the dynamical susceptibility. When both the Zeeman field and the wave vector of the incident microwave are parallel to the anisotropy axis, the first four moments determine the shift of the resonance frequency and the linewidth in a situation where the frequency is varied for fixed Zeeman field. For the one-dimensional model we can calculate the moments exactly. This provides exact data for the resonance shift and the linewidth at arbitrary temperatures and magnetic fields. In current ESR experiments the Zeeman field is varied for fixed frequency. We show how in this situation the moments give perturbative results for the resonance shift and for the integrated intensity at small anisotropy as well as an explicit formula connecting the linewidth with the anisotropy parameter in the high-temperature limit.

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Magnetic resonance in quantum spin chains

Cited by 9 publications

References 119 publications

Absorption of microwaves by the one-dimensional spin-12Heisenberg-Ising magnet

Absorption of microwaves by the one-dimensional spin-12Heisenberg-Ising magnet

Coherent spin dynamics of solitons in the organic spin chain compounds(o-DMTTF)2X(X=Cl,Br)

Theory of Microwave Absorption by the Spin-1/2Heisenberg-Ising Magnet

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