Charge Density Waves in Solids


Book Description

Neutron and x-ray scattering study on K0.3MoO3 and other quasi one dimensional conductors -- X-ray study of charge-density wave in K0.30Mo03 under electric fields -- Transmission electron microscopy for imaging and diffraction studies of low dimensional transition metal chalcogenides -- Aspects of charge-density waves in the TaTe4-NbTe4 structures and in 2H-TaSe2 -- Charge density waves, phasing, sliding and related phenomena in NbSe3 and other transition metal chalcogenides -- Structural and electrical properties interpretation through band structure calculations on the (MSe4)nI SERIES (M = Nb, Ta). -- Defects and charge density waves in irradiated layer and chain compounds -- Electron diffraction charge density wave studies in the chalcogenide compounds (MX4)nI -- Neutron studies of the blue bronzes K0.3MoO3 and Rb0.3MoO3 -- The effect of a magnetic field on the discotm1ensurate to commensurate transition in 2H TaSe2 -- High pressure investigation of the cdw phase diagram of 1T-TaS2 -- Landau theory of 2H-TaSe2 -- Multidomain structures of incommensurate phases in CDW states of 2H-TaSe2 -- Electron microscopy of charge density wave defects in 1T-TaS2 and 1T-TaSe2 -- Aspects of strong electron-phonon coupling related to the CDW transition at temperatures above it -- Elastic and other properties at the commensurate-incommensurate transition in 2H-TaSe2 -- CDW phase mode investigation in the FIR in K0.3MaO3 and band structure calculation -- 93Nb NMR study of CDW in (NbSe4)10/3I single crystal -- Electronic Properties and Fe57 Mössbauer measurements of T1+xNb3-xSe10 with T = Fe, Cr -- Transport and Mössbauer studies of the peierls transition in Fe-doped K0.30MoO3 -- Charge density wave instabilities in quasi two-dimensional oxides n-Mo4O11 and ?-Mo4O11 -- Thermal conductivity of layered dichalcogenides -- Tunneling study of commensurate charge density wave states in 1T-TaS2 -- Galvanomagnetic properties of the quasi-two dimensional purple bronze K0.9Mo6O17 -- Non-local elastic forces in charge-density wave systems -- Soliton model of charge-density-wave depinning -- Dynamics of incommensurate structures -- Some problems arising from electrostatic potential in CDW behavior -- The single domain model of charge-density wave transport -- On the microscopic theory of kinetic phenomena in peierls conductors -- Near commensurability effects on charge density wave dynamics -- Shift in the longitudinal sound velocity due to sliding charge density waves -- Microscopic local mechanisms for "Noises" generated by moving CDW -- Phase vortices and CDW conduction noise -- Damping of CDW-condensate motion by interaction with thermal phasons -- Microscopic theory of interaction of CDW with impurities -- Quantum effects in the Josephson approach to a CDW -- Fokker planck theory of the classical charge density wave model with current noise -- Travelling charge density waves : A mean field treatment -- Coherent and incoherent effects in charge density wave transport -- Threshold field, electrical conductivity and time-dependent voltage in transition metal tri- and tetrachalcogenides -- Solitons in TaS3 experiment -- Thermal gradient experiments on the charge-density-wave conduction noise spectrum -- Broadband noise in orthorhombic TaS3 -- High field I-V characteristics of orthorhombic TaS3 -- Inertial dynamics of CDW transport in NbSe3 -- Frequency dependent conductivity of CDW compounds -- AC conductivity of the blue bronze K0.3 MoO3 -- Subharmonic shapiro steps, devil's staircase, and synchronization in RF-driven CDW conductors -- Mode locking and chaos in sliding charge-density-wave systems -- Chaos in charge density wave systems -- Contribution of CDW motion to the hall effect and to the transverse conductivity in TaS3. experiment -- Contribution of CDW motion to the hall effect and to the transverse conductivity. Theory -- Dependence of the elastic modulus of TaS3 on the CDW current -- Low frequency elastic properties of materials containing a sliding CDW -- The conductivity of orthorhombic TaS3 under uniaxial strain -- Ohmic and nonlinear transport of (TaSe4)2I under pressure -- Pinning, metastability and sliding of charge-density-waves -- Distortion, metastability and breaking in charge-density wave transport: Recent experiments on niobium triselenide, suggesting a new mean-field approach -- Bistable configurations of the pinned charge density wave: Random-field-model dynamics observed in rearrangement prior to depinning -- Electric field induced relaxation of metastable states in TaS3 -- Remanent deformation of CDWs -- Relaxation of the deformed cdw state: electric and thermal hysteresis -- Thermal hysteresis in the thermopower of o-TaS3 -- Delayed switching between normal and CDW conducting states in o-TaS3 -- The effect of uniaxial strain on metastable states in TaS3 -- Influence of defects on the metastable states of o-TaS3 -- Charge density wave transport in the blue bronzes K0.30MoO3 and Rb0.30MoO3 : metastability, hysteresis and memory effects -- Effects of irradiation on the blue bronzes K0.30MoO3 and Rb0.30MoO3 -- Relaxation of metastable states in blue bronze K0.3MoO3 -- Incommensurate ferroelectrics -- Commensurate and incommensurate phases of a two-dimensional lattice of superconducting vortices -- (TMTSF)2X compounds: Superconductivity, spin-density waves and anion ordering -- Impurity pinning in quasi-1D superconductivity -- Numerical studies of the effect of a wall on SDW in a jellium -- Pinning of amplitude solitons in Peierls systems with impurities -- New resistive state in low dimensional superconductor TaSe3 -- Switching in cdw systems and in V02 -- A comparative study -- The effect of varying the bandfilling in a Peierls conductor -- Solitons and polarons in a spin density wave chain -- Charge density waves in superionic conductors -- Numerical study of impurity pinning in one-dimensional interacting electron systems -- Multivalued charge-density waves.




Transport Studies and Phenomenological Model for Sliding Charge-density Waves in Quasi-one-dimensional Conductors


Book Description

Transport studies examining the dynamics of one-dimensional charge-density wave (CDW) condensates are reported. Results using rf and dc, linear and nonlinear electrical transport techniques have been obtained at temperatures below the CDW transition in the quasi-one-dimensional materials o-TaS$sb3$, K$sb{0.03}$MoO$sb3$, (IaSe$sb4)sb2$I and NbSe$sb3$. Each of these materials exhibits a different set of CDW parameters due to differences in structural properties and electronic band structure. By correlating results obtained on these four materials systems and by considering a detailed overview of other experimental work in the field, the generic features of charge-density wave dynamics have been elucidated. A phenomenological model based on strong impurity pinning of the CDW phase is presented as a possible framework for resolving a long-standing debate over the correct theoretical description for CDW transport. Essentially all of the experimental results known to date on CDW systems can be interpreted within this framework. Numerical estimates are made from the model accurately reproducing the observed generic features of CDW dynamics. A brief summary is made of the shortcomings that have faced various other classical and quantum mechanical models. The study provides a solid reference point for future advances in microscopic charge-density wave theory. Sliding CDWs constitute only the second known example of a moving quantum ground state, the first being superconductivity. Unlike superconductivity, sample impurities break the translational invariance of an incommensurate CDW and pin it to the underlying crystal lattice. The universal features of the dynamics seen in CDW conductors are indeed very rich. Nonlinear conductivity occurs above a dc threshold for both deformable motion at high temperatures and rigid motion in fully gapped materials at low temperature. The ac response of the pinned CDW has a very complex behavior with up to three characteristic pinning frequencies and associated damping constants. Dielectric relaxation proves to be the most important element in properly describing the CDW phase dynamics, including motion of the charge-density wave in the periodic impurity pinning potential.




Low-Dimensional Conductors and Superconductors


Book Description

Research activities in low dimensional conductors have shown a rapid growth since 1972 and have led to the discovery of new and remarkable phy sical properties unique to both molecular and inorganic conductors exhibi ting one-dimensional transport behaviour. This NATO Institute was a conti nuation of aseries of NATO Advanced Study Institutes of Worshops which took place at regular intervals till 1979. This is the first time, however, that charge density wave transport and electronic properties of low dimen sional organic conductors are treated on an equal footing. The program of the Institute was framed by tutorial lectures in the theories and experiments of low dimensional conductors. The bulk of the course covered two series of low-dimensional mate rials with their respective properties. 1) The I-D inorganic conductors exhibiting the phenomena of sliding charge density waves, narrow band noise, memory effects, etc ..• 2) Low-dimensional crystallized organic conductors giving rise to various possibilities of ground states, spin-Peierls, spin density wave, Peierls, superconductivity and magnetic-field induced spin density wave, etc ... Since it has been established from the beginning that this Institute was to be devoted essentially to the Physics of Low Dimensional Conductors, only one main course summarized the progress in chemistry and material preparation.







Physics and Chemistry of Low-Dimensional Inorganic Conductors


Book Description

The field of low-dimensional conductors has been very active for more than twenty years. It has grown continuously and both the inorganic and organic materials have remark able properties, such as charge and spin density waves and superconductivity. The discovery of superconductivity at high temperature in copper-based quasi two-dimensional conducting oxides nearly ten years ago has further enlarged the field and stimulated new research on inorganic conductors. It was obviously impossible to cover such a broad field in a ten day Institute and it seemed pertinent to concentrate on inorganic conductors, excluding the high Tc superconducting oxides. In this context, it was highly desirable to include both physics and chemistry in the same Institute in order to tighten or in some cases to establish links between physicists and chemists. This Advanced Study Institute is the continuation of a series of similar ones which have taken place every few years since 1974. 73 participants coming from 13 countries have taken part in this School at the beautiful site of the Centre de Physique des Houches in the Mont-Blanc mountain range. The scientific programme included more than forty lectures and seminars, two poster sessions and ten short talks. Several discussion sessions were organized for the evenings, one on New Materials, one on New Topics and one on the special problem of the Fermi and Luttinger liquids. The scientific activity was kept high from the beginning to the end of the Institute.




Charge Density Waves in Solids


Book Description

The latest addition to this series covers a field which is commonly referred to as charge density wave dynamics. The most thoroughly investigated materials are inorganic linear chain compounds with highly anisotropic electronic properties. The volume opens with an examination of their structural properties and the essential features which allow charge density waves to develop. The behaviour of the charge density waves, where interesting phenomena are observed, is treated both from a theoretical and an experimental standpoint. The role of impurities in statics and dynamics is considered and an examination of the possible role of solitons in incommensurate charge density wave systems is given. A number of ways to describe charge density waves theoretically, using computer simulations as well as microscopical models, are presented by a truely international board of authors.




Emergent States in Photoinduced Charge-Density-Wave Transitions


Book Description

This book advances understanding of light-induced phase transitions and nonequilibrium orders that occur in a broken-symmetry system. Upon excitation with an intense laser pulse, materials can undergo a nonthermal transition through pathways different from those in equilibrium. The mechanism underlying these photoinduced phase transitions has long been researched, but many details in this ultrafast, non-adiabatic regime still remain to be clarified. The work in this book reveals new insights into this phenomena via investigation of photoinduced melting and recovery of charge density waves (CDWs). Using several time-resolved diffraction and spectroscopic techniques, the author shows that the light-induced melting of a CDW is characterized by dynamical slowing-down, while the restoration of the symmetry-breaking order features two distinct timescales: A fast recovery of the CDW amplitude is followed by a slower re-establishment of phase coherence, the latter of which is dictated by the presence of topological defects in the CDW. Furthermore, after the suppression of the original CDW by photoexcitation, a different, competing CDW transiently emerges, illustrating how a hidden order in equilibrium can be unleashed by a laser pulse. These insights into CDW systems may be carried over to other broken-symmetry states, such as superconductivity and magnetic ordering, bringing us one step closer towards manipulating phases of matter using a laser pulse.