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Di Yin Changzhen Li Junfeng Wang Rui Xiong Jing Shi Congzhi Bi XiangGang Qiu 《Journal of Physics and Chemistry of Solids》2009,70(1):249-3786
Polarized infrared reflectivity measurements between 300 and 10 K have been carried out on charge density waves (CDW) conductor blue bronze Tl0.3MoO3. Three important features are observed: (i) A bump at 1155 cm−1 in the reflectivity spectra of Tl0.3MoO3 at 300 K is a precursor of the Peierls gap due to optical excitations across a pseudogap, and this kind of Peierls-like gap opens gradually with decreasing temperature from 180 to 160 K. (ii) The three sharp modes as “triplet” of infrared reflectivity between 800 and 1000 cm−1 of Tl0.3MoO3 along [1 0 2] axis show red shift compared to K0.3MoO3 and Rb0.3MoO3, which is assigned to the increase of the distance of Mo-O bond with the substitution of thallium ions. (iii) Two peaks at about 514 and 644 cm−1 in the far-infrared reflectivity spectra of Tl0.3MoO3 along [1 0 2] direction are suggested to be the electronic transitions from the valence band to the midgap state and from occupied midgap state to the conduction band, respectively. 相似文献
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The optical reflectivity of the blue bronze K0.3MoO3 has been measured on single crystals for photon energies between 0.03 and 12 eV at temperatures from 10 to 300 K using polarized light. The data are interpreted that this compound is a one-dimensional conductor for temperatures above 180 K and that the metal-semiconductor transition at 180 K is due to a Peierls type transition, leading to a gap of 0.15 eV in the density of states. 相似文献
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Raman scattering measurements on the one-dimensional (1-D) blue bronze K0.3MoO3 are reported as function of temperature. At about 50 cm-1 a Raman line of Ag(A) symmetry was found with an anomalous temperature dependence. The line symmetry, the softening of the eigenfrequency and the apparent disappearing of the coupling constant at the critical temperature, allow us to assign this line to the amplitude mode of the CDW, predicted by the theory of the Peierls transition. A Peierls precursor at room temperature was also observed and is discussed. 相似文献
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通过I-V特性测量,研究了横向交、直流电流对蓝青铜K0.3MoO3中电荷密度波(CDW)动力学行为的影响.实验结果表明,无论是直流还是交流,随着横向调制电流的增大,CDW滑移的阈值电场均会相应地减小;但横向交流电流的调制效应较小,可能更接近本征的效应.考察了横向交流电流的调制效应与其频率的依赖关系.
关键词:
0.3MoO3单晶')" href="#">K0.3MoO3单晶
电荷密度波
横向电流调制效应 相似文献
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D. Starešinić D. Dominko K. Salamon K. Biljaković A. Tomeljak H. Schäfer T. Huber J. Demsar G. Socol C. Ristoscu I.N. Mihailescu Z. Siketić I. Bogdanović Radović G. Pletikapić V. Svetličić M. Đekić H. Šamić J. Marcus 《Physica B: Condensed Matter》2012,407(11):1889-1893
Thin granular films of charge density wave (CDW) system K0.3MoO3 were prepared by pulsed laser deposition and investigated by various standard characterization methods such as GI-XRD, electric transport, TOF-ERDA, AFM and UV–visible spectroscopy. While all these methods indicate that the thin films consist of nanometer grains of K0.3MoO3, it is only the non-destructive femtosecond time-resolved spectroscopy (fsTRS) that demonstrates the charge density wave nature of the ground state and therefore proves directly the presence of K0.3MoO3. Furthermore, the comparison of the fsTRS data obtained in thin films and in single crystals shows the reduction of the charge density wave transition temperature and of the photoinduced signal strength in granular thin films with respect to single crystals, which is attributed to the granularity and crystal growth morphology. Our results establish fsTRS technique as the essential tool for the detection and characterization of complex ground states in nano-sized systems. 相似文献
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The optical reflectivity of the red bronze K0.33MoO3 has been measured on single crystals in the spectral energy range between 0.03 and 12 eV at temperatures from 4 K to 300 K using polarized light. The optical constants have been determined by means of a Kramers-Kronig analysis; the data are interpreted that this compound is a 0.5 eV energy gap semiconductor with very strong anisotropy in the infrared and visible energy range. 相似文献
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G. Remenyi 《Physics letters. A》2009,373(46):4278-4281
The charge density wave (CDW) dynamics of the quasi-one-dimensional conductor K0.30MoO3 shows two different regimes depending on the temperature: a strongly damped CDW motion above ∼50 K and CDW motion with almost no damping below ∼50 K. In a search for a characterization of this CDW behaviour, we performed thermal expansion measurements on K0.30MoO3 single crystals in the temperature range 4-250 K. In addition to the anomaly observed at the Peierls transition at 180 K along the [102] direction, an anomaly is observed at ∼50 K along the [−201] and [102] directions. The results are discussed in relation with the change in the CDW rigidity at ∼50 K. 相似文献
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Y.Y. Koh W.S. Jung S.R. Park Chul Kim W.S. Kyung L.X. Yang F. Chen C. Kim 《Journal of Physics and Chemistry of Solids》2011,72(5):565-567
We report growth and angle resolved photoemission studies of Cu intercalated NbSe2. CuxNbSe2 with x=0, 0.04 and 0.08 were grown by iodine vapor transport method. Intercalation and doping was confirmed by the change in the c-axis lattice constant and the change in the electronic structure, respectively. To investigate the nesting condition, we performed auto-correlation analysis on the data. We find that the magnitude of the nesting vector decreases with doping but the direction remains unchanged. Our observation is consistent with the nesting coming from intra-pocket transition. 相似文献
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Junfeng Wang Di Yin Zhengyou Liu Decheng Tian Yuheng Zhang 《Solid State Communications》2004,132(10):653-656
The thermoelectric power (TEP) of the quasi-one-dimensional charge-density-wave (CDW) conductors rubidium blue bronze Rb0.3MoO3 and its alloy Rb0.15K0.15MoO3 were measured in the temperature range 80-280 K. The result showed a sign change from a small positive value to a great negative value where the Peierls transition temperatures (Tp) are 183 and 180 K for Rb0.3MoO3 and Rb0.15K0.15MoO3, respectively. Above Tp, the TEP for both samples can be described with the empirical relation S=AT+B; while below Tp, the TEP fits well the relation S=AT+B/T based on the experimental data. The Fermi energies εF for Rb0.3MoO3 and Rb0.15K0.15MoO3 are estimated to be 1.55 and 0.53 eV, respectively. 相似文献
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Aleksej Mialitsin 《Journal of Physics and Chemistry of Solids》2011,72(5):568-571
Low energy Raman scattering from the ab-plane of the 2H polytype single crystal NbSe2 has been investigated in the normal (N), incommensurate charge density wave (ICDW) and superconducting (SC) phases. The temperature dependence of the polarization resolved Raman response has been obtained for the excitation wavelength of 647 nm and fitted to phenomenological models for the E2g and A1g symmetry channels. The A1g response can be fitted by a simple damped oscillator peak superimposed on continuous background. The E2g response displays an anti-resonance interference pattern between the inter-layer phonon and the CDW-induced mode such that a hybridized configuration (Fano line shape [1]) is required for modelling. The polarization specific peak maxima positions and line widths as a function of temperature, deduced in this manner, are presented. Partial suppression of the electronic continuum scattering in the Raman shift range up to 110 cm−1 in the A1g symmetry channel and beyond 300 cm−1 in the E2g symmetry channel is indicative of high energy electronic states far away from the Fermi surface participating in the ICDW formation. 相似文献
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We report size effects on the charge-density-wave pinning in the quasi-one-dimensional conductor K0.30MoO3 in the temperature range 77 K-160 K. The threshold field is approximately one order of magnitude larger in needle-like samples than in bulk crystals, temperature independent and strongly dependent on the width of the sample. In addition, the nonlinear conductivity shows a maximum near 130 K. The results are discussed in relation with various pinning models and CDW dislocations. 相似文献
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T. Tamegai K. Tsutsumi S. Kagoshima Y. Kanai H. Tomozawa M. Tani Y. Nogami M. Sato 《Solid State Communications》1985,56(1):13-16
A deformation of the CDW is investigated under the electric field whose magnitude is intensionally made inhomogeneous in the one-dimensional conductor K0.30MoO3. It is verified that the CDW's deformation, which occurs in the transverse (2a1-c1)-direction, is caused by the field gradient in the sample. In the sample where the CDW deformation is found without the intensional inhomogeneity of the electroc field, the deformation is not uniform from point to point. Possible relations are discussed between the structural change and the electrical polarization observed in pulse measurements of the conductivity. 相似文献
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F.J. DiSalvo J.V. Waszczak K. Yamaya 《Journal of Physics and Chemistry of Solids》1980,41(12):1311-1313
The magnetic susceptibility of NbSe3 shows a decrease beginning slightly above its upper charge density wave transition (CDW) of 144 K, but no change within our resolution near the 59 K transition. The change in the density of states at the Fermi level due to the upper transition is 0.14 states-eV/Nb. TaSe3 on the other hand has a temperature independent susceptibility. In some cases the trichalcogenides are contaminated with their corresponding dichalcogenide. Such contamination can be observed by susceptibility measurements in the case of 2HTaSe2 but not of 2HNbSe2. We also report an anomaly in the susceptibility of 4HaNbSe2, which suggests a CDW transition at 45 K. 相似文献
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In this paper, we examine the variation of threshold fields and the transient response of tungsten- and rubidium- substituted K0.30MoO3. We find that the dc threshold electric field for the onset of nonlinear behavior scales linearly with tungsten concentration, but varies as the square of the rubidium concentration, indicating strong and weak pinning effects, respectively. In tungsten- substituted samples, the threshold field becomes a strong function of frequency in the range 0.01– 1000 Hz. Above a critical frequency which depends on the doping level, the threshold field is proportional to -log (frequency). We interpret these results as a further example of the spin glass- like response of the CDW. Nonlinear conductivity is observed only after the voltage has exceeded the threshold for a finite time interval. 相似文献
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Sylvain Ravy Claire Laulhé Jean-Paul Itié Pierre Fertey Benoit Corraze Sabrina Salmon Laurent Cario 《Physica B: Condensed Matter》2012,407(11):1704-1706
We present a room temperature high-pressure X-ray diffraction study of the layered compound 1T-TaS2 up to 20 GPa. This material is known to exhibit a variety of structural phase transitions that are ascribed to the stabilization of charge density wave states. It has been recently shown that at pressures larger than 3 GPa and up to 25 GPa, 1T-TaS2 becomes superconductor below about 5 K. It was suggested that this superconductivity coexists with different CDW states, an hypothesis that can be tested by X-ray diffraction. Our first results at room temperature show that at around 1.9 GPa, the nearly-commensurate (NCCDW) phase transforms into a phase similar to the high temperature incommensurate phase (ICCDW). Above 9 GPa, we show the existence of another IC phase, still discernable up to 20 GPa despite the pressure-induced crystal damage above 13 GPa. These results are consistent with resistivity measurements, but call for a complete exploration of the P–T phase diagram of 1T-TaS2. 相似文献
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Slow relaxation phenomena as well as quasiperiodic noise have been studied in the non linear regime of conductivity which takes place above a well defined threshold electric field in the semiconducting incommensurate phase of the quasi one-dimensional blue bronze K0.30MoO3. The noise frequencies are found to be proportional to the excess current attributed to the charge density wave (CDW). In some temperature range, the CDW current is found to decrease logarithmically vs time. These results indicate the presence of metastable states related to domains and domain walls. 相似文献