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.
















Low Frequency Charge-density Wave Dynamics


Book Description

The low frequency dynamics of the charge-density waves in NbSe$sb3$ and TaS$sb3$ were investigated using low frequency conductance fluctuations. Simultaneous measurements of the fluctuations in the voltage and the differential resistance revealed a theory of threshold voltage fluctuations can only partially describe some of the fluctuations in the I-V curve. Noise measurements performed with an ac drive current characterized the fluctuations and showed that other parameters, in addition to the threshold, must be fluctuating to fully account for the fluctuations. In mesoscopic samples, the observation of discrete switching in the voltage allowed estimates of the dynamical coherence length ranging from $rm{approx}100mu m$ up to the entire sample length of $rm{approx}1000mu m.$ Experiments to determine if the low frequency dynamics are equilibrium or nonequilibrium processes showed that the dynamics involve a combination of equilibrium and nonequilibrium dynamics. The equilibrium dynamics can be described by a rough free energy landscape with extreme sensitivity of the local details of the landscape to changes in the temperature or current. The nonequilibrium dynamics were directly related to the drive current.













Time Resolved Dynamics of Charge Density Waves in Solids


Book Description

Charge density wave (CDW) is a periodic charge modulation in a metal, induced by electron-phonon or electron-electron interaction, which breaks the translational symmetry of the underlying electron gas. The charge density wave order is ubiquitous among condensed matter systems, and its equilibrium properties have been well characterized by static probes, such as X-ray scattering. However, little is known about their nonequilibrium properties following photoexcitation. In this thesis, we use time resolved optical measurements to characterize the nonequilibrium dynamics of charge density wave systems. In the time resolved optical experiments in this work, an ultrashort (