|Jun12-12, 04:05 AM||#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...
|Jun13-12, 07:58 AM||#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.
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.