Colloids

Colloidal crystals are an ideal system in which to study the general problem of ordering and dynamics in 2D, since the particle size permits direct imaging of the particle locations and motion. A considerable amount of work has been conducted on the melting of 2D colloidal crystals in the absence of a substrate. In addition, a number of experimental and theoretical studies have considered colloidal crystallization and melting in 2D systems with periodic 1D and 2D substrates, where a rich variety of crystalline states can be stabilized. Colloid crystals are also ideal for studing the ordering and dynamics of an elastic media interacting with random substrates, a problem that is relevant to a wide variety of systems such as superconducting vortices, Wigner crystals, and charge-density waves. Open issues include the nature of the dynamical response to applied forces, as well as whether an order to disorder transition occurs as the strength of the random substrate increases.

Preprints:

1. Enhancing mixing and diffusion with plastic flow
   A. Libal, C. Reichhardt, and C.J. Olson Reichhardt
   arxiv:0706.2681
   We use numerical simulations to examine two-dimensional particle mixtures that strongly phase separate in equilibrium. When the system is externally driven in the presence of quenched disorder, plastic flow occurs in the form of meandering and strongly mixing channels. In some cases this can produce a fast and complete mixing of previously segregated particle species, as well as an enhancement of transverse diffusion even in the absence of thermal fluctuations. We map the mixing phase diagram as a function of external driving and quenched disorder parameters.

Papers:

1. Disordering transitions and peak effect in polydisperse particle systems
   C. Reichhardt and C.J. Olson Reichhardt
   arxiv:0704.3622
   Phys. Rev. E 77, 041401 (2008).

2. Defect fluctuations and lifetimes in disordered Yukawa systems
   C. Reichhardt and C.J. Olson Reichhardt
   cond-mat/0605026
   Phys. Rev. E 75, 051407 (2007).

3. Stripes, clusters, and nonequilibrium ordering for bidisperse colloids with repulsive interactions
   C. Reichhardt and C.J. Olson Reichhardt
   cond-mat/0610351
   Phys. Rev. E Rapid Communications 75, 040402 (2007).

4. Point defect dynamics in two-dimensional colloidal crystals
   A. Libal, C. Reichhardt, and C.J. Olson Reichhardt
   cond-mat/0609676
   Phys. Rev. E 75, 011403 (2007).

5. Realizing colloidal artificial ice on arrays of optical traps
   A. Libal, C. Reichhardt, and C.J. Olson Reichhardt
   cond-mat/0603265
   Phys. Rev. Lett. 97, 228302 (2006).

6. Cooperative behavior and pattern formation in mixtures of driven and nondriven colloidal assemblies
   C. Reichhardt and C.J. Olson Reichhardt
   cond-mat/0602118
   Phys. Rev. E 74, 011403 (2006).

7. Dynamics, rectification, and fractionation for colloids on flashing substrates
   A. Libal, C. Reichhardt, B. Janko, and C.J. Olson Reichhardt
   cond-mat/0508299
   Phys. Rev. Lett. 96, 188301 (2006).

8. Heterogeneities and topological defects in two-dimensional pinned liquids
   J.-X. Lin, C. Reichhardt, Z. Nussinov, L.P. Pryadko, and C.J. Olson Reichhardt
   cond-mat/0601104
   Phys. Rev. E 73, 061401 (2006).
   

9. Coarsening of topological defects in oscillating systems with quenched disorder
   C. Reichhardt and C.J. Olson Reichhardt
   cond-mat/0505743
   Phys. Rev. E 73, 046122 (2006).
   

10. Crossover from intermittent to continuum dynamics for locally driven colloids
    C. Reichhardt and C.J. Olson Reichhardt
    cond-mat/0505174
    Phys. Rev. Lett. 96, 028301 (2006).
    

11. Ratchet effect and nonlinear transport for particles on random substrates with crossed ac drives
    C. Reichhardt and C.J. Olson Reichhardt
    cond-mat/0509311
    Phys. Rev. E 73, 011102 (2006).
    

12. Pinning and dynamics of colloids on one dimensional periodic potentials
    C. Reichhardt and C.J. Olson Reichhardt
    cond-mat/0409561
    Phys. Rev. E 72, 032401 (2005).
    

13. Glassy ratchets for collectively interacting particles
    C. Reichhardt, C.J. Olson Reichhardt, and M.B. Hastings
    cond-mat/0308097
    Phys. Lett. A 342, 162 (2005).

14. Ordering and melting in colloidal molecular crystal mixtures
    C. Reichhardt and C.J. Olson Reichhardt
    cond-mat/0412104
    Phys. Rev. E 71, 062403 (2005).
    

15. Statics and dynamics of colloidal particles in periodic traps
    C. Reichhardt and C.J. Olson Reichhardt
    Proc. SPIE 5514, 352 (2004).
    Online version
    

16. Reentrant disordering of colloidal molecular crystals on two-dimensional periodic substrates
    M. Mikulis, C.J. Olson Reichhardt, C. Reichhardt, R.T. Scalettar, and G.T. Zimanyi
    J. Phys.: Condens. Matter 16, 7909 (2004).
    Online version

17. Dynamic regimes and spontaneous symmetry breaking for driven colloids on triangular substrates
    C. Reichhardt and C.J. Olson Reichhardt
    Europhys. Lett. 68, 303 (2004).
    Online version

18. Nonlinear dynamics, rectification, and phase locking for particles on symmetrical two-dimensional periodic substrates with dc and circular ac drives
    C. Reichhardt, C.J. Olson Reichhardt, and M.B. Hastings
    Phys. Rev. E 69, 056115 (2004).
    Online version

19. Directional locking effects and dynamics for particles driven through a colloidal lattice
    C. Reichhardt and C.J. Olson Reichhardt
    Phys. Rev. E 69, 041405 (2004).
    Online version
    

20. Local melting and drag for a particle driven through a colloidal crystal
    C. Reichhardt and C.J. Olson Reichhardt
    Phys. Rev. Lett. 92, 108301 (2004).
    Online version
    

21. Structure and melting of two-species charged clusters in a parabolic trap
    J.A. Drocco, C.J. Olson Reichhardt, C. Reichhardt, and B. Janko
    Phys. Rev. E 68, 060401(R) (2003).
    Images of colloid configurations
    Online version
    

22. Absolute transverse mobility and ratchet effect on periodic 2D symmetric substrates
    C. Reichhardt and C.J. Olson Reichhardt
    Phys. Rev. E 68, 046102 (2003).
    Online version
    

23. Frustration and melting of colloidal molecular crystals
    C.J. Olson Reichhardt and C. Reichhardt
    J. Phys. A: Math. Gen. 36, 5841 (2003).
    Online version

24. Depinning by fracture in a glassy background
    M.B. Hastings, C.J. Olson Reichhardt, and C. Reichhardt
    Phys. Rev. Lett. 90, 098302 (2003).
    Online version
    

25. Fluctuating topological defects in 2D liquids: Heterogeneous motion and noise
    C. Reichhardt and C.J. Olson Reichhardt
    Phys. Rev. Lett. 90, 095504 (2003).
    Online version
    

26. Colloidal dynamics on disordered substrates
    C. Reichhardt and C.J. Olson
    Phys. Rev. Lett. 89, 078301 (2002).
    Online version
    

27. Rectification and phase locking for particles on two dimensional periodic substrates
    C. Reichhardt, C.J. Olson, and M.B. Hastings
    Phys. Rev. Lett. 89, 024101 (2002).
    Online version

28. Novel colloidal crystalline states on two dimensional periodic substrates
    C. Reichhardt and C.J. Olson
    Phys. Rev. Lett. 88, 248301 (2002).
    Online version
    

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