Fokker planck theory of the classical charge density wave model with current noise

Predictions of the charge density wave (CDW) model for potassium are tested by high-field induced torque experiments. The CDW model is described to show the open orbits on the Fermi surface of potassium with a CDW. Expressions for the induced torque are developed in terms of the resistivity and other parameters of the sample. The induced torque as a function of magnetic field direction shows sharp structure above 3–4 T with more than 20 peaks in 180° rotation. The peaks have the character of open orbits and the large number is predicted by the CDW model. The magnetic field, sample orientation, and temperature dependences of induced torque are also investigated. The magnetic field dependence agrees with that expected from open orbits with magnetic breakdown. However, the open orbits that would cause the induced torque peaks are not in directions predicted by the CDW model. Variation of induced torque with temperatures between 1.4 and 2.1 K can be explained by some of the features of the model although the observed changes are larger than those predicted. The conclusion is that the CDW model explains many of the properties of the high-field induced torque structure.

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Vector Charge Density Wave Model of Metallic and Trigonal Te

Progress of Theoretical Physics ◽

10.1143/ptp/87.2.307 ◽

1992 ◽

Vol 87 (2) ◽

pp. 307-329 ◽

Cited By ~ 11

Author(s):

Y. Shimoi ◽

H. Fukutome

Keyword(s):

Charge Density ◽

Charge Density Wave ◽

Density Wave ◽

Wave Model ◽

Vector Charge

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Incommensurate modulated phases of the NbxTa1-xTe4 charge density wave system

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100120692 ◽

1992 ◽

Vol 50 (1) ◽

pp. 58-59

Author(s):

S. Ritchie ◽

J. C. Bennett ◽

A. Prodan ◽

F.W. Boswell ◽

J.M. Corbett

Keyword(s):

Charge Density ◽

Charge Density Wave ◽

Direct Evidence ◽

Density Wave ◽

Wave System ◽

Modulated Phases ◽

Metal Atoms ◽

Incommensurate Modulation ◽

End Members ◽

Modulation Wave Vector

A continuous sequence of compounds having composition NbxTa1-xTe4; 0 ≤ x ≤ 1 have been studied by electron diffraction and microscopy. Previous studies have shown that the end members of the series, TaTε4 and NbTε4 possess a quasi-one-dimensional character and exhibit charge density wave (CDW) distortions. In these compounds, the subcell structure is tetragonal with axes (a × a × c) and consists of the metal atoms (Nb or Ta) centered within an extended antiprismatic cage of Te atoms. At room temperature, TaTε4 has a commensurate modulation structure with a 2a × 2a × 3c unit cell. In NbTε4, an incommensurate modulation with × ∼ 16c axes is observed. Preliminary studies of the mixed compounds NbxTα1-xTε4 showed a discontinuous jump of the modulation wave vector commensurate to incommensurate when the Nb dopant concentration x, exceeded x ≃ 0.3, In this paper, the nature of the compositional dependence of is studied in greater detail and evidence is presented for a stepwise variation of . This constitutes the first direct evidence for a Devil's staircase in CDW materials.

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