What is commensurate and incommensurate cdw or sdw?

  • Context: Graduate 
  • Thread starter Thread starter sarir_sss
  • Start date Start date
Click For Summary
SUMMARY

The discussion clarifies the concepts of commensurate and incommensurate charge density waves (CDW) and spin density waves (SDW). Commensurate refers to periodicity that is a multiple of the host crystal's unit cell, while incommensurate indicates the opposite. The sliding of an incommensurate CDW can be induced by applying a voltage, affecting the displacement vector defined by u(r) = u_0 cos(k*r + phi), where the phase phi changes over time. Pinning occurs at defects, hindering sliding, and coupling often refers to the interaction between SDW and CDW, exemplified by chromium metal.

PREREQUISITES
  • Understanding of charge density waves (CDW) and spin density waves (SDW)
  • Familiarity with crystal lattice structures and unit cells
  • Knowledge of wave vectors and periodicity in solid-state physics
  • Basic principles of voltage application in condensed matter systems
NEXT STEPS
  • Research the effects of voltage on incommensurate charge density waves
  • Study the role of defects in pinning phenomena in CDW and SDW systems
  • Explore the coupling mechanisms between spin density waves and charge density waves
  • Investigate the properties of chromium metal as a prototype for CDW and SDW interactions
USEFUL FOR

Physicists, materials scientists, and researchers in condensed matter physics focusing on wave phenomena in crystalline materials.

sarir_sss
Messages
7
Reaction score
0
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...
 
Physics news on Phys.org
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.
 

Similar threads

  • · Replies 5 ·
Replies
5
Views
2K
  • · Replies 6 ·
Replies
6
Views
9K
  • · Replies 4 ·
Replies
4
Views
3K
  • · Replies 1 ·
Replies
1
Views
1K
  • · Replies 11 ·
Replies
11
Views
4K
  • · Replies 5 ·
Replies
5
Views
4K
  • · Replies 6 ·
Replies
6
Views
3K
  • · Replies 3 ·
Replies
3
Views
2K
  • · Replies 2 ·
Replies
2
Views
2K
  • · Replies 9 ·
Replies
9
Views
2K