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Cdw sdw

  1. Jun 12, 2012 #1
    what is commensurate and incommensurate cdw or sdw?what means?
    what means"sliding cdw or sdw"?
    what is" coupling "in cdw or sdw?
    what is" pinning" in cdw or sdw?
    any help u could give would b much approciated...
     
  2. jcsd
  3. Jun 13, 2012 #2
    cdw = charge density wave = periodic displacement of ions

    sdw = spin density wave = periodic arrangement of spin (antiferromagnet).

    commensurate means that the periodicity is a multiple of the host crystal's unit cell.

    incommensurate means the opposite.

    An incommensurate cdw can be made to slide by applying a voltage.

    If the displacement vector u at position r is given by u(r) = u_0 cos(k*r + phi), then sliding means that the phase phi is changing with time.

    Pinning can occur at defects and may prevent sliding.

    http://iopscience.iop.org/0295-5075/56/2/289/

    Coupling can mean many many things....

    Many times a sdw with wave vector k (period lambda) will induce a cdw with wave vektor 2k (period lambda/2) as secondary order parameter. Chromium metal is the prototype for such a system.
     
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