Magnetic ordering and fluctuations in the S=1/2 square Heisenberg antiferromagnet Cu(DCO2)2.4D2O

Clarke, Simon J.; Harrison, Andrew; Mason, T.E.; McIntyre, Garry J.; Visser, Dick

doi:10.1088/0953-8984/4/4/003

Cited by 23 publications

(16 citation statements)

References 23 publications

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“…As regards CFTD, we can assume a value around J = 80 K. Estimates based on the velocity of the spin waves [11] are in the same range, as well as old data [12] (within 10%), in agreement with the dispersion curve determined by neutron scattering near the zone boundary (H. M. Rönnow, pers. commun.).…”

Section: Analysis Of the Data And Comparison With The Theoretical Expsupporting

confidence: 72%

Correlated spin dynamics in 2-D quantum Heisenberg antiferromagnets from NMR relaxation in copper formiate tetradeuterate

et al. 2000

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Proton nuclear magnetic resonance (NMR) T, in a single crystal of copper formiate tetradeuterate is used to study the correlated Cu e spin dynamics and to derive the temperature behavior of the in-plane magnetic correlation length. The results are compared with the predictions of recent theoretical models for the spin dynamics in planar quantum Heisenberg antiferromagnets in a wide temperature range (from the Néel temperature up to a reduced temperature T/J -1.4, with J in-plane exchange integral). In particular, it is shown that, in contrast to the predictions of the nonlinear a model, no crossover to a quantum critical regime occurs and that the experimental findings are well reproduced by deriving the NMR relaxation rate in the framework of the standard mode-mode coupling theory.

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Section: Analysis Of the Data And Comparison With The Theoretical Expsupporting

confidence: 72%

Correlated spin dynamics in 2-D quantum Heisenberg antiferromagnets from NMR relaxation in copper formiate tetradeuterate

et al. 2000

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“…Analogous methods to evaluate J in CFTD are under way [26]. At the moment in CFTD we can assume a value around J = 80 K. Estimates based on the velocity of the spin waves [27] are in the same range, as well as old data [28](within 10%), in agreement with the dispersion curve determined by neutron scattering near the zone-boundary [26].…”

mentioning

confidence: 72%

Spin Dynamics and Magnetic Correlation Length in Two-Dimensional Quantum Heisenberg Antiferromagnets

Carretta

Ciabattoni

Cuccoli³

et al. 2000

Phys. Rev. Lett.

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The correlated spin dynamics and the temperature dependence of the correlation length ξ(T ) in two-dimensional quantum (S = 1/2) Heisenberg antiferromagnets (2DQHAF) on square lattice are discussed in the light of experimental results of proton spin lattice relaxation in copper formiate tetradeuterate (CFTD). In this compound the exchange constant is much smaller than the one in recently studied 2DQHAF, such as La2CuO4 and Sr2CuO2Cl2. Thus the spin dynamics can be probed in detail over a wider temperature range. The NMR relaxation rates turn out in excellent agreement with a theoretical mode-coupling calculation. The deduced temperature behavior of ξ(T ) is in agreement with high-temperature expansions, quantum Monte Carlo simulations and the pure quantum self-consistent harmonic approximation. Contrary to the predictions of the theories based on the Non-Linear σ Model, no evidence of crossover between different quantum regimes is observed.In recent years, it has been argued that the pairing mechanism leading to high-temperature superconductivity can occur in the presence of quantum critical fluctuations, as the ones expected in two-dimensional quantum (S = 1/2) Heisenberg antiferromagnets (2DQHAF) [1,2]. This early observation has triggered a novel interest on the correlated spin dynamics in 2DQHAF. Several studies have been carried out on the behavior of the magnetic correlation length ξ as a function of temperature and/or disorder, and on the possibility of driving quantum phase transitions by hole doping. In particular, for a given degree of disorder (i.e. doping) the temperature is expected to cause the transition to a regime with peculiar quantum spin excitations, which could be responsible for novel pairing mechanisms [3]. In spite of an enormous amount of experimental and theoretical efforts this issue is still controversial [4,5]. Thus, it is believed that it is necessary first to unravel the problem of the spin dynamics and of the temperature dependence of ξ(T ) in pure 2DQHAF.The 2DQHAF with nearest-neighbor interaction on square lattice, is described by the Hamiltonianwith J > 0 and a = (0, ±a), (±a, 0), a being the lattice constant. The 2DQHAF has been commonly described in terms of the 2-dimensional Quantum Non-Linear σ Model (QNLσM) [6], with the action given bywhere n(x) is a unitary 3D vector field, g = c s Λ/ρ s and u = c s Λ/T are the coupling and the imaginary-time cutoff respectively. This mapping is rigorous only in the large-spin limit, where ρ s and c s are the spin stiffness and the spin-wave velocity of the correspondent magnetic model. This approach can be extended to S = 1/2 provided that c s and ρ s are introduced as fitting parameters. Then a rich and interesting phase diagram can be devised [2,7,8]. Accordingly, the QNLσM has arisen to a great popularity, both for basic quantum magnetism studies as well as a good candidate to describe the modifications in the microscopic properties of a 2DQHAF when it becomes a high-T c superconductor upon charge doping. One of the most striking pr...

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“…This is largely due to the intense interest in understanding the properties of the CuO 2 layers in the high temperature superconductors. However, the experimental motivation is not limited to these cuprate compounds; recent investigations [4][5][6][7][8] have refocussed interest on a number of other layered insulating compounds which are rather well described as Heisenberg antiferromagnets at low temperatures 9 . The bulk of the existing theoretical work on two dimensional antiferromagnets can be divided into two broad classes:…”

Section: Introductionmentioning

confidence: 99%

Theory of two-dimensional quantum Heisenberg antiferromagnets with a nearly critical ground state

1994

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We present the general theory of clean, two-dimensional, quantum Heisenberg antiferromagnets which are close to the zero-temperature quantum transition between ground states with and without long-range Néel order. While some of our discussion is more general, the bulk of our theory will be restricted to antiferromagnets in which the Néel order is described by a 3-vector order parameter. For Néel-ordered states, 'nearly-critical' means that the ground state spin-stiffness, ρ s , satisfies ρ s ≪ J, where J is the nearest-neighbor exchange constant, while 'nearly-critical' quantum-disordered ground states have a energy-gap, ∆, towards excitations with spin-1, which satisfies ∆ ≪ J. The allowed temperatures, T , are also smaller than J, but no restrictions are placed on the values of k B T /ρ s or k B T /∆. Under these circumstances, we show that the wavevector/frequency-dependent uniform and staggered spin susceptibilities, and the specific heat, are completely universal functions of just three thermodynamic parameters. On the ordered side, these three parameters are ρ s , the T = 0 spin-wave velocity c, and the ground state staggered moment N 0 ; previous works have noted the universal dependence of the susceptibilities on these three parameters only in the more restricted regime of k B T ≪ ρ s . On the disordered side the three thermodynamic parameters are ∆, c, and the spin-1 quasiparticle residue A. Explicit results for the universal scaling functions are obtained by a 1/N expansion on the O(N ) quantum non-linear sigma model, and by Monte Carlo simulations. These calculations lead to a variety of testable predictions for neutron scattering, NMR, and magnetization measurements. Our results are in good agreement with a number of numerical simulations and experiments on undoped and lightly-doped La 2−δ Sr δ CuO 4 .

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Magnetic ordering and fluctuations in the S=1/2 square Heisenberg antiferromagnet Cu(DCO₂)₂.4D₂O

Cited by 23 publications

References 23 publications

Correlated spin dynamics in 2-D quantum Heisenberg antiferromagnets from NMR relaxation in copper formiate tetradeuterate

Correlated spin dynamics in 2-D quantum Heisenberg antiferromagnets from NMR relaxation in copper formiate tetradeuterate

Spin Dynamics and Magnetic Correlation Length in Two-Dimensional Quantum Heisenberg Antiferromagnets

Theory of two-dimensional quantum Heisenberg antiferromagnets with a nearly critical ground state

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