Spin-Peierls transition in N-methyl-N-ethyl-morpholinium-ditetracyanoquinodimethanide [MEM-<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow><mml:mn /><mml:mo>(</mml:mo><mml:mi mathvariant="normal">TCNQ</mml:mi><mml:mo>)</mml:mo><mml:mn /></mml:mrow><mml:mrow><mml:mn>2</mml:mn></mml:mrow></mml:msub></mml:mrow></mml:math>]

Huizinga, S.; Kommandeur, Jan; Sawatzky, G. A.; Thole, B. T.; Kopinga, K.; Jonge, W. J. M. de; Roos, J.

doi:10.1103/physrevb.19.4723

Cited by 275 publications

(98 citation statements)

References 22 publications

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“…This transition was experimentally observed for the first time in charge-transfer complexes (TTF)[M{S 2 C 2 (CF 3 ) 2 }] (TTF = tetrathiafulvalene) (M = Cu, Au) [6,7] and MEM-(TCNQ) 2 (MEM = methyl-ethylmorpholinium) [8]. Decades later, the spin-Peierls transition was observed also in inorganic compounds, firstly in CuGeO 3 [9], which is a main representant of spinPeierls inorganic systems, and later also in (VO) 2 P 2 O 7 [10], which is a model system of interacting chains.…”

Section: Accepted Manuscriptmentioning

confidence: 99%

Two-gap magnetic structure of the two-stack anion-radical salt (N-Me-3,5-Di-Me-Py)(TCNQ)2 (Py is pyridine)

Radváková¹,

Kazheva²,

Chekhlov³

et al. 2010

Journal of Physics and Chemistry of Solids

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Section: Accepted Manuscriptmentioning

confidence: 99%

Two-gap magnetic structure of the two-stack anion-radical salt (N-Me-3,5-Di-Me-Py)(TCNQ)2 (Py is pyridine)

Radváková¹,

Kazheva²,

Chekhlov³

et al. 2010

Journal of Physics and Chemistry of Solids

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“…27.+a First observed in the 70's in the organic compounds MEM(TCNQ) 2 [1] and TTF-CuBDT [2], [3] and later in the charge transfer salts (TMTTF) 2 PF 6 [4], (TMTTF) 2 AsF 6 [5] and (BCP-TTF) 2 X [6], [7] (where X=PF 6 and AsF 6 ), the spin-Peierls (SP) transition regained interest after its discovery in the inorganic system CuGeO 3 [8]. The SP ground state is a magnetoelastic distortion of a one-dimensional (1D) antiferromagnetic chain of spin-1/2.…”

mentioning

confidence: 99%

X-ray investigation of the magnetoelastic instability ofα′−NaV2O5<

1999

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We present an X-ray diffuse scattering study of the pretransitional structural fluctuations of the magneto-elastic transition in α ′ -NaV2O5. This transition is characterized by the appearance below Tsp ∼ 35K of satellite reflections at the reduced wave vector (1/2,1/2,1/4). A large regime of structural fluctuations is measured up to 90 K. These fluctuations are three dimensional between Tsp and ∼ 50K and quasi-one dimensional above ∼ 60K. At 40 K the anisotropy ratio ( ξ b : ξa : ξc) is found to be ( 3.8 : 1.8 : 1 ), which reveals the importance of transverse interactions in the stabilization of the low temperature phase. We discuss our results within the framework of recent theories dealing with the simultaneous occurrence of a charge ordering, a spin gap and a lattice distortion in this intriguing compound. [7] (where X=PF 6 and AsF 6 ), the spin-Peierls (SP) transition regained interest after its discovery in the inorganic system CuGeO 3 [8]. The SP ground state is a magnetoelastic distortion of a one-dimensional (1D) antiferromagnetic chain of spin-1/2. Below the transition temperature T c a singlet-triplet gap opens in the magnetic excitation spectrum, accompanied by a lattice doubling of the chain. Theoretically, the SP transition is driven by one-dimensional antiferromagnetic fluctuations coupled to the lattice via the spin-phonon coupling. Accordingly, a strong and anisotropic regime of lattice fluctuations is expected to occur. Nevertheless, SP systems do not all exhibit such a regime of fluctuations as we already emphasized in a previous study [9]. In MEM(TCNQ) 2 and TTF-CuBDT the temperature dependence of the magnetic susceptibility χ(T ) down to T c is well accounted for by a Bonner-Fisher (BF) law of a one-dimensional S=1/2 Heisenberg chain. However, an isotropic x-ray diffuse scattering at the location of the low temperature superlattice reflection remains until high temperature [9] [3]. On the other hand, in (BCP-TTF) 2 AsF 6 a quasi-one dimensional fluctuation regime is observed and χ(T ) exhibits a sizeable deviation from the BF law, interpreted as due to the influence of the lattice fluctuations on the spin degrees of freedom [10]. As far as CuGeO 3 is concerned, an anisotropic fluctuation regime has been observed until ∼ 2.5T c [11]. Here again, χ(T ) does not follow the BF law due to either deviation from one-dimensionality or to the presence of sizeable next-nearest neighbor interactions. All these results show that, although the spin-Peierls transition concept was successfully used to describe all these magneto-elastic transitions, the experimental situation is much more intricate.The inorganic compound α ′ -NaV 2 O 5 has recently been shown to undergo a magneto-elastic phase transition at T c = 34K [12]. Above T c , χ(T ) follows remarkably the BF law (with the exchange constant J/k B =280 K) and the abrupt decrease of χ(T ) below T c is accompanied by a lattice doubling observed by x-ray diffraction [13]. Moreover, the existence of a spin gap ∆ of ∼ 10 meV was evidenced by inelastic neu...

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“…Below 335 K, the compound undergoes a metal-insulator transition that dimerized the TCNQ chains [23], but leaves the spins degrees of freedom unaffected down to T SP ≈ 18K, where a second transition tetramerizes the chains and shows all the characteristics of the SP distorted state [24]. However, not much is known on the SP gap in this system [5,25].…”

Section: Introductionmentioning

confidence: 98%

“…3). In zero field, these procedures give an average temperature, T SP (0) = 17.9 ± 0.1 K, a value falling within the range 17.1 -18 K found from other techniques [5,23,26]. In the framework of mean-field theory of quasi-one-dimensional SP systems [6,20], the SP temperature is predicted to decay quadratically with the magnetic field according to the expression,…”

Section: B Ultrasonic Velocitymentioning

confidence: 99%

“…A modification of the coupling between the charge and the SP lattice distortion in a presence of a magnetic field, and not the zero-temperature value of the SP order parameter, may be responsible for this slight increase of polarizability at low temperatures. Although the origin of the low temperature Curie tail in the dielectric response remains to be clarified, it should be mentioned that in the same temperature range a Curie tail has also been reported in the spin sector for the magnetic susceptibility [23]. For these dielectric experiments, the determination of the zero field transition temperature T SP (0) is particularly difficult because of the slow power law in the reduced temperature (x 0.85) and the presence of substantial critical scattering below and above the transition.…”

Section: A Dielectric Constantmentioning

confidence: 99%

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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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Spin-Peierls transition in N-methyl-N-ethyl-morpholinium-ditetracyanoquinodimethanide [MEM-(TCNQ)2]

Cited by 275 publications

References 22 publications

Two-gap magnetic structure of the two-stack anion-radical salt (N-Me-3,5-Di-Me-Py)(TCNQ)2 (Py is pyridine)

Two-gap magnetic structure of the two-stack anion-radical salt (N-Me-3,5-Di-Me-Py)(TCNQ)2 (Py is pyridine)

X-ray investigation of the magnetoelastic instability ofα′−NaV2O5<

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

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