[PDF] Equilibrium And Non Equilibrium Dynamics Of Charge Density Waves In Chromium eBook

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Page : 109 pages
File Size : 17,13 MB
Release : 2013
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ISBN : 9781303634444

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Below I present two related studies on the dynamics of spin-/charge-density-waves (SDW/CDW) in chromium. In the first study we measured equilibrium fluctuations of antiferromagnetic SDW/CDW domains in a bulk sample by correlating speckle patterns obtained with partially coherent synchrotron x-rays. The autocorrelation functions follow a double compressing exponential decay similar to that observed in other `jammed' condensed matter systems. This hyper-diffusive behavior indicates the existence of collective relaxation modes which we interpret to arise from the coherent rotation of weakly coupled blocks of spins. Time scales for this collective process range from tens of seconds at 150 Kelvin to thousands of seconds at low temperatures. Even near absolute zero, we observed fluctuations of the magnetic structure which can most directly be interpreted as arising from quantum mechanical zero-point motion. Because microscopic domains of energetically similar spin/charge ordered states are quantum mechanically linked, there exists a dynamic competition between alternate ground states that provides insight into the free energy landscape of domain wall configurations. We obtain estimates of the effective soliton mass of a domain wall and the Arrhenius activation energy.

Author : Gero Storeck
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Page : pages
File Size : 38,63 MB
Release : 2020
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In recent years, charge-density wave (CDW) systems have been studied extensively, as they provide a diverse testing field for basic concepts in electron-phonon coupling, electron correlation, and structural phase transitions. In particular, time-resolved techniques have participated in that process, disentangling the dynamics of the various degrees of freedoms in such complex materials. As a recently developed pump-probe technique, ultrafast low-energy electron diffraction provides complementary insight into the CDW-coupled structural dynamics at the surface. This cumulative thesis covers t...

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Page : 13 pages
File Size : 28,50 MB
Release : 1996
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The magnetic phase diagrams of all dilute Cr alloys can be explained by a simple theoretical model with coupled spin- and charge-density waves and a finite electron reservoir. If the charge-density wave and electron reservoir are sufficiently large, the paramagnetic to commensurate spin-density wave transition becomes strongly first order, as found in Cr{sub 1- x}Fe(subscript x) and Cr{sub 1-x}Si(subscript x) alloys. The observed discontinuity of the slope dT{sub N}/dx at the triple point and the bending of the CI phase boundary are also natural consequences of this model.

Author : Alwyn Scott
Publisher : Routledge
Page : 1107 pages
File Size : 29,86 MB
Release : 2006-05-17
Category : Reference
ISBN : 1135455589

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In 438 alphabetically-arranged essays, this work provides a useful overview of the core mathematical background for nonlinear science, as well as its applications to key problems in ecology and biological systems, chemical reaction-diffusion problems, geophysics, economics, electrical and mechanical oscillations in engineering systems, lasers and nonlinear optics, fluid mechanics and turbulence, and condensed matter physics, among others.

Author : Alexander Altland
Publisher : Cambridge University Press
Page : 785 pages
File Size : 26,37 MB
Release : 2010-03-11
Category : Science
ISBN : 0521769752

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This primer is aimed at elevating graduate students of condensed matter theory to a level where they can engage in independent research. Topics covered include second quantisation, path and functional field integration, mean-field theory and collective phenomena.