Spin-Peierls Transition in Alkali-TCNQ Salts

Takaoka, Y.; Motizuki, Kazuko

doi:10.1143/jpsj.47.1752

Cited by 36 publications

(13 citation statements)

References 22 publications

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“…However, it is easier in this formulation to treat other functional dependences of J on intersite spacing, and a few authors have done this for exponential and power-law dependences. [51][52][53] Since Eqs. (1) and (7) We have defined the SP transition rigorously as a magnetically driven spin-lattice dimerization of antiferromagnetic chains.…”

Section: Ju +mentioning

confidence: 99%

The Spin-Peierls Transition

Bray

Interrante

Jacobs

et al. 1983

Extended Linear Chain Compounds

104

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Section: Ju +mentioning

confidence: 99%

The Spin-Peierls Transition

Bray

Interrante

Jacobs

et al. 1983

Extended Linear Chain Compounds

104

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“…p in the high-temperature (T) phase could be explained by assuming a uniform antiferromagnetic spin (S 1=2) chain, indicating the SP nature of this transition [10]. Other theoretical studies also suggested that this transition is driven by the SP mechanism [11,12].…”

mentioning

confidence: 94%

Ultrafast Photoinduced Melting of a Spin-Peierls Phase in an Organic Charge-Transfer Compound, K-Tetracyanoquinodimethane

et al. 2006

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Ultrafast photoinduced phase transition in a spin-Peierls (SP) system of K-tetracyanoquinodimethane (K-TCNQ) was studied by femtosecond (fs) reflection spectroscopy. Photocarriers destabilize the SP phase, resulting in a decrease in molecular dimerization within 400 fs. Such a melting of the SP phase drives three kinds of coherent oscillations. By comparing the oscillations with the Raman bands activated by the dimerization, we show that the oscillation of 20 cm-1 is due to an LO phonon, and it plays an important role for the stabilization of the SP phase.

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“…An SP transition is of the second-order and the transition temperature T p is usually very low, typically lower than 20 K. 23 The phase transitions of M-TCNQ have been regarded as a kind of SP transitions. [24][25][26] Actually, the phase transitions of M-TCNQ are of the first order and their transition temperatures are very high, so that they are not typical SP transitions. To explain the features of the phase transitions of M-TCNQ, the importance of the charge degree of freedom 27 and the structural nature of the transition 19 have been suggested.…”

Section: Introductionmentioning

confidence: 99%

“…It is, however, reasonable to consider that the SP mechanism plays important roles on their transitions. [24][25][26] In an SP phase, photocarriers will be able to stimulate the instability of the SL system through the breaking of the spinsinglet states and then the ultrafast melting of the SP phase by photoirradiation is expected to occur. 9 In fact, photoinduced destabilization of the SP phase was reported in K-TCNQ ͑Refs.…”

Section: Introductionmentioning

confidence: 99%

Ultrafast photoinduced melting of spin-Peierls phase in the organic charge-transfer compounds alkali-tetracyanoquinodimethane

et al. 2007

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Photoinduced phase transitions in spin-Peierls ͑SP͒ systems of alkali ͑M =K,Na͒-tetracyanoquinodimethane ͑TCNQ͒ have been studied by a reflection-type femtosecond ͑fs͒ pump-probe spectroscopy. The SP phase is destabilized by the generation of photocarriers through the breaking of the spin-singlet states in dimers. It results in the decrease of the dimeric molecular displacements within a few hundred of femtoseconds over several tens of TCNQ molecules. It is accompanied by the displacive-type coherent oscillations, which consist mainly of three modes with the frequencies of 20, 49, and 90 cm −1 in K-TCNQ and of two modes with the frequencies of 49 and 99 cm −1 in Na-TCNQ. By taking into account the temperature dependence of the Raman scattering spectra, the mode with 20 cm −1 in K-TCNQ and the modes with 49 and 99 cm −1 in Na-TCNQ are assigned to the phonon modes in the SP ground state, while the modes with 49 and 90 cm −1 in K-TCNQ are assigned to the local modes originating from the photoexcited states. Polarization dependence of the Raman scattering signals shows that the 20-cm −1 mode of K-TCNQ and the 49-cm −1 mode of Na-TCNQ are longitudinal optical ͑LO͒ modes, whereas the 99-cm −1 mode of Na-TCNQ is a transverse optical ͑TO͒ mode. Namely, the LO mode plays an important role on the stabilization of the SP phase in K-TCNQ, while both the LO and TO modes in Na-TCNQ. Such a difference is discussed by scrutinizing the difference of the crystal structures and the nature of the SP transitions in the two compounds.

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Spin-Peierls Transition in Alkali-TCNQ Salts

Cited by 36 publications

References 22 publications

The Spin-Peierls Transition

The Spin-Peierls Transition

Ultrafast Photoinduced Melting of a Spin-Peierls Phase in an Organic Charge-Transfer Compound, K-Tetracyanoquinodimethane

Ultrafast photoinduced melting of spin-Peierls phase in the organic charge-transfer compounds alkali-tetracyanoquinodimethane

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