Spin diffusion in one-dimensional antiferromagnets

Narozhny, B. N.

doi:10.1103/physrevb.54.3311

Cited by 26 publications

(20 citation statements)

References 15 publications

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“…42 For the Heisenberg model, the absence of spin diffusion has been probed by bosonization techniques 49 and numerical calculations. 50 Reference 50 presents exact numerical computations for the spin-1/2 XXZ chain at infinite temperature (Tϭϱ), which include, as particular cases, the isotropic Heisenberg model and the XY regime, which are gapless, and the Heisenberg-Ising model, with a gap in the spectrum and long-range order for the ground state.…”

Section: Final Discussionmentioning

confidence: 99%

Long-time tails and anomalous slowing down in the relaxation of spatially inhomogeneous excitations in quantum spin chains

Berim¹,

Berim

Cabrera

2002

Phys. Rev. B

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Exact analytic calculations in spin-1/2 XY chains show the presence of long-time tails in the asymptotic dynamics of spatially inhomogeneous excitations. The decay of inhomogeneities for t→ϱ, is given in the form of a power law (t/ Q ) Ϫ Q , where the relaxation time Q and the exponent Q depend on the wave vector Q, characterizing the spatial modulation of the initial excitation. We consider several variants of the XY model ͑dimerized, with staggered magnetic field, with bond alternation, and with isotropic and uniform interactions͒, that are grouped into two families, whether the energy spectrum has a gap or not. Once the initial condition is given, the nonequilibrium problem for the magnetization is solved in closed form, without any other assumption. The long-time behavior for t→ϱ can be obtained systematically in a form of an asymptotic series through the stationary phase method. We found that gapped models show critical behavior with respect to Q, in the sense that there exist critical values Q c where the relaxation time Q diverges and the exponent Q changes discontinuously. At those points, a slowing down of the relaxation process is induced, similarly to phenomena occurring near phase transitions. Long-lived excitations are identified as incommensurate spin density waves that emerge in gapped systems, as a consequence of both approximate nesting of the spectrum and the degeneracy of some stationary points. In contrast, gapless models do not present the above anomalies as a function of the wave vector Q.

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Section: Final Discussionmentioning

confidence: 99%

Long-time tails and anomalous slowing down in the relaxation of spatially inhomogeneous excitations in quantum spin chains

Berim¹,

Berim

Cabrera

2002

Phys. Rev. B

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“…It may originate from spin diffusion [16,17] or fluctuations of the energy density of the spin system [18]. The former mechanism is forbidden in perfect 1D spin systems and leads to a Gaussian line shape [19] of the central line, while the latter leads to a Lorentzian [18], and is important for systems with nonnegligible spinphonon coupling. Spin-phonon coupling leads to an enhancement of the spectral weight of the energy fluctuations by reducing their time scale [20].…”

Section: Magnetic Raman Scatteringmentioning

confidence: 99%

Low-dimensional magnetism of spin-½ chain systems of α- and β-TeVO4: A comparative study

Gnezdilov

Lemmens

Wulferding

et al. 2012

Low Temperature Physics

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We present a comparative study of the low-dimensional compounds α-and β-TeVO 4 . Our data clearly show that the change in the local coordination geometry of V 4+ ions comparing α-and β-TeVO 4 leads to a drastic differences in the magnetic properties. Despite sharing the same crystal structure, the two compounds realize different magnetic exchange topologies. Both compounds exhibit a transition from ferro-to antiferromagnetic correlations with decreasing temperature. This effect however is driven by different mechanisms for both compounds. Additionally, a dimensional crossover is found in β-TeVO 4 . PACS

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“…However, only recently a considerable progress in the theoretical understanding of the transport properties of 1D quantum spin systems has been made. 27,28,29,30,31,32,33,34,35,36,37,38 The main focus of these recent studies has been on the relationship of the spin transport and conservation laws, 27,28 specifically on the possibility of an ideal conducting state in one-dimensional integrable and non-integrable systems. 31,32,33 While this problem is of significant interest, the importance of the spin-phonon and spin-impurity couplings, which break down the integrability of the underlying spin-only models, has also been discussed.…”

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confidence: 99%

Thermal transport in antiferromagnetic spin-chain materials

Chernyshev

Rozhkov

2005

Phys. Rev. B

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We study the problem of heat transport in one-dimensional (1D) spin-chain systems weakly coupled to three-dimensional phonons and impurities. We consider the limit of fast spin excitations and slow phonons, applicable to a number of compounds of the cuprates family, such as Sr2CuO3, where the superexchange J is much larger than the Debye energy, ΘD. In this case the Umklapp scattering among the spin excitations is strongly suppressed for all relevant temperatures. We argue that the leading scattering mechanism for the spin excitations at not too low temperatures is the "normal" (as opposed to the Umklapp) spin-phonon scattering in which the non-equilibrium momentum is transferred from the spin subsystem to phonons where it quickly relaxes through the "phonon bath". Because of the lower dimensionality of the spin excitations it is only the momentum along the chains which is conserved in such a scattering. We find that this effect leads to a particular momentum-and temperature-dependence of the spin-phonon relaxation rate valid for the broad class of low-dimensional spin systems. Subsequently we demonstrate that the spin-phonon relaxation mechanism is insufficient for the low-energy, long-wavelength 1D spin-chain excitations, which make the thermal conductivity diverge. We complete our consideration by taking into account the impurity scattering, which in 1D cuts off the quasi-ballistic spin excitations and renders the thermal conductivity finite. Altogether, these effects yield the following spin-boson thermal conductivity behavior: κs ∝ T 2 at low temperatures, κs ∝ T −1 at intermediate temperatures, and κs = const at higher temperatures T ∼ ΘD. The saturation at higher temperatures is of rather non-trivial origin and we provide a detailed discussion of it. Our results compare very well with the existing experimental data for Sr2CuO3. Using our microscopic insight into the problem we propose further experiments and predict an unusual impurity concentration dependence for a number of quantities.

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Spin diffusion in one-dimensional antiferromagnets

Cited by 26 publications

References 15 publications

Long-time tails and anomalous slowing down in the relaxation of spatially inhomogeneous excitations in quantum spin chains

Long-time tails and anomalous slowing down in the relaxation of spatially inhomogeneous excitations in quantum spin chains

Low-dimensional magnetism of spin-½ chain systems of α- and β-TeVO4: A comparative study

Thermal transport in antiferromagnetic spin-chain materials

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