The Spin-Peierls Transition

Bray, J. W.; Interrante, L. V.; Jacobs, I. S.; Bonner, Jill C.

doi:10.1007/978-1-4684-4175-8_7

Cited by 104 publications

(46 citation statements)

References 137 publications

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“…An adiabatic (Born-Oppenheimer) approximation for the lattice is typically invoked to model the Peierls [39] or spin-Peierls [12,40] instability of 1D systems, although quantum fluctuations [41] are important for small δ(0) at T = 0. The BOW phase has finite δ(0) for linear electron-phonon (e-ph) coupling α to a harmonic lattice [30], where α = (dt/du) 0 is the first term of the Taylor expansion of t(R + u).…”

Section: Magnetic Susceptibilitymentioning

confidence: 99%

“…The transitions are [9] at T d = 348 K and 395 K, respectively, for Na and K-TCNQ. Torrance [10] and others [11] sought to model T d as a spin-Peierls transition, as discussed in the review of Bray et al [12] who noted that such high T d requires unacceptably large exchange constants. The transitions have some 3D character since the cations also dimerize [13,14].…”

Section: Introductionmentioning

confidence: 99%

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Magnetic susceptibility of alkali-tetracyanoquinodimethane salts and extended Hubbard models with bond order and charge density wave phases

Kumar

Topham

et al. 2011

The Journal of Chemical Physics

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The molar spin susceptibilities χ(T ) of Na-TCNQ, K-TCNQ and Rb-TCNQ(II) are fit quantitatively to 450 K in terms of half-filled bands of three one-dimensional Hubbard models with extended interactions using exact results for finite systems. All three models have bond order wave (BOW) and charge density wave (CDW) phases with boundary V = Vc(U ) for nearest-neighbor interaction V and on-site repulsion U . At high T , all three salts have regular stacks of TCNQ − anion radicals. The χ(T ) fits place Na and K in the CDW phase and Rb(II) in the BOW phase with V ≈ Vc. The Na and K salts have dimerized stacks at T < T d while Rb(II) has regular stacks at 100K. The χ(T ) analysis extends to dimerized stacks and to dimerization fluctuations in Rb(II). The three models yield consistent values of U , V and transfer integrals t for closely related TCNQ − stacks. Model parameters based on χ(T ) are smaller than those from optical data that in turn are considerably reduced by electronic polarization from quantum chemical calculation of U , V and t on adjacent TCNQ − ions. The χ(T ) analysis shows that fully relaxed states have reduced model parameters compared to optical or vibration spectra of dimerized or regular TCNQ − stacks.

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Section: Magnetic Susceptibilitymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Magnetic susceptibility of alkali-tetracyanoquinodimethane salts and extended Hubbard models with bond order and charge density wave phases

Kumar

Topham

et al. 2011

The Journal of Chemical Physics

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“…The J 2c results agree with theory within our improved numerical accuracy up to at least δ = 0.10, which is well into the regime of spin-Peierls systems. [22][23][24] As previously noted, 2,4,20 the ST gap at J 2 = 0 is more accurately represented by Eq. (2) than by scaling theory with logarithmic corrections.…”

Section: And 3 Bozonization and Conformal Field Theories Have Motivamentioning

confidence: 66%

“…(2) In terms of physical realizations, spin-Peierls systems [22][23][24] with strong coupling to the lattice and δ ~ 0.10 at low T are required in order to minimize competition from second neighbor or interchain exchange or from anisotropic or antisymmetric corrections to J. shown. …”

Section: Figmentioning

confidence: 99%

Scaling exponents in spin-12Heisenberg chains with dimerization and frustration studied with the density-matrix renormalization group

et al. 2007

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In conformal field theory, key properties of spin-1/2 chains, such as the ground state energy per site and the excitation gap scale with dimerization δ as δ α with known exponents α and logarithmic corrections. The logarithmic corrections vanish in a spin chain with nearest (J=1) and next nearest neighbor interactions (J 2 ), for J 2c =0.2411.DMRG analysis of a frustrated spin chain with no logarithmic corrections yields the field theoretic values of α, and scaling relation is valid up to the physically realized range, δ ~ 0.1. However, chains with logarithmic corrections (J 2 <0.2411J) are more accurately fit by simple power laws with different exponents for physically realized dimerizations. We show the exponents decreasing from approximately 3/4 to 2/3 for the spin gap and from approximately 3/2 to 4/3 for the energy per site and error bars in the exponent also decrease as J 2 approaches to J 2c .

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“…The SP state has been formerly investigated in a few organic materials (TTF-CuBDT, TTF-AuBDT, MEM(TCNQ) 2 [1,2], and more recently in an inorganic compound CuGeO 3 [3]. Despite different crystals structures, very similar physical properties are observed.…”

Section: Introductionmentioning

confidence: 99%

Charge, spin, and lattice effects in the spin-Peierls ground state of MEM(TCNQ)2

et al. 2013

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We report an investigation of charge, spin and lattice effects in the spin-Peierls state of the organic compound MEM(TCNQ)2. The 16.5 GHz dielectric function along the chain axis shows an enhancement below the spin-Peierls transition temperature near 18 K consistent with the charge coupling to the elastic strain involved in the transition. The velocity of two elastic modes perpendicular to the chain axis presents anomalies at the transition which can be explained with a Landau free energy model including a linear-quadratic coupling energy term between the appropriate elastic strain e and the spin-Peierls magnetic gap ∆q. The analysis of the dielectric and elastic features aims toward an order parameter with an associated critical exponent β ∼ 0.36, which is similar to the threedimensional behavior seen in other spin-Peierls materials. All these effects studied in a magnetic field up to 18 Teslas appear also compatible with a mean-field model of a quasi-one-dimensional spin-Peierls system.

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The Spin-Peierls Transition

Cited by 104 publications

References 137 publications

Magnetic susceptibility of alkali-tetracyanoquinodimethane salts and extended Hubbard models with bond order and charge density wave phases

Magnetic susceptibility of alkali-tetracyanoquinodimethane salts and extended Hubbard models with bond order and charge density wave phases

Scaling exponents in spin-12Heisenberg chains with dimerization and frustration studied with the density-matrix renormalization group

Charge, spin, and lattice effects in the spin-Peierls ground state of MEM(TCNQ)2

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