Rashmi C. Desai

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Condensed Matter Physics (Theoretical)

Professor: B.Sc. , Bombay (1957); Ph.D. Cornell (1966). Coordinator of Graduate Studies (1983-87); Associate Chair (Graduate Studies) (1992-1997); Visiting Professor , Caltech (1975); Visiting Scientist , IBM, San Jose (1981-82); Visiting Professor, Uni. of Mainz, Germany (1987); Uni. of Texas at Austin (1998); Uni. of Arizona (1999).

Physics of Complex Fluids, Statistical Physics of Phase Transitions, Domain Growth and Interface Dynamics. Instabilities, Nonlinearities, Pattern Selection and Spatio-Temporal Chaos. Numerical Simulations.

Research Interests

Physics of complex fluids is an exciting area which has many fundamental research problems and which also happens to be of technological interest. Polymers, liquid crystals, colloidal suspensions like ferrofluids, micellar systems, microemulsions, and Langmuir monolayers are some of the examples of complex fluids. This research area involves applying the knowledge in nonequilibrium and equilibrium statistical physics, elasticity theory, hydrodynamics and electromagnetism to specific problems.

Research problems of our current interest include the following: the role of fluctuations in polymer phase diagrams; kinetics of phase ordering and phase separation including spinodal decomposition and nucleation; pattern formation and selection in nonequilibrium phase transitions; instabilities in dynamical systems leading to chaos, and control of chaos.

Many of the projects also have biophysical implications. Thermodynamic instabilities and metastabilities often play crucial role. Sometimes thermal noise becomes important and often long range competing interactions bring in new characteristic length scales making qualitative changes in kinetics. Invariably, dynamics of and at interfaces in these systems are also of fundamental importance in understanding physics of complex fluids. For recent completed projects, see the list of Selected Publications. Some of the future projects are: spinodal decomposition in Polymer Dispersed Liquid Crystals (PDLC), surface tension induced Marangoni instability, elasticity of rod-reinforced-matrix composites and elastic effects in soft stressed solids (like gels, microemulsions), nonequilibrium physics of fracture.

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Spinodal decomposition for an off-critical quench. The domain boundary evolution, shown at various times, displays a crossover from an interconnected morphology to one with separated droplets.

Recent Publications

  1. R.C. DESAI, F. James and E. Lui, Biological Ageing: A Bit-String Model with Fertility and Fecundity, Theory in Biosciences, 118, 97-112 (1999).
  2. F. Léonard and R.C. DESAI, Implications of a Model for Instability during Film Growth for Strained InGaAs and SiGe Layers, Appl. Phys. Letters, 74, 40-42 (1999).
  3. O. Schönborn and R.C. DESAI, Intra-surface Kinetics of Phase Ordering, J. Stat. Phys., 95, 949-979 (1999).
  4. O. Schönborn and R.C. DESAI, Curvature Autocorrelations in Domain Growth Dynamics, European Physical Journal, B9, 719-724 (1999).
  5. F. Léonard and R.C. DESAI, Spinodal Decomposition and Dislocation Lines in Thin Films and Bulk Materials, Phys. Rev. B, B58, 8277-8288 (1998).
  6. F. Léonard and R.C. DESAI, Atomic Ordering and Surface Instabilities in Thin Films, Physics in Canada, 54, 230-232 (1998).
  7. F. Léonard and R.C. DESAI, Atomic Ordering and the Surface Morphology of Thin Films, Appl. Phys. Letters, 73, 208-210 (1998).
  8. M. Laradji and R.C. DESAI, Elastic Properties of Homopolymer-Homopolymer Interfaces Containing Diblock Copolymers, J. Chem. Phys., 108, 4662-4674 (1998).
  9. F. Léonard and R.C. DESAI, Alloy Decomposition and Surface Instabilities in Thin Films, Phys. Rev. B, B57, 4805-4815 (1998).
  10. M. Laradji, R.C. DESAI, A.-C. Shi, and J. Noolandi, Stability of Ordered Phases in Weakly Segregated Diblock Copolymer Systems, - a comment, Phys. Rev. Letters, 80, 202 (1998).
  11. R.C. DESAI, Langmuir Films, Physics in Canada, 53, 210-221 (1997), an invited refereed paper.
  12. R.C. DESAI, Anisotropic Fluctuations and Stability of Ordered Phases in Diblock Copolymer Systems, Physica A A244, 81-90 (1997). An invited paper in honour of Professor B. Widom's 70th birthday feitschrift.
  13. F. Léonard and R.C. DESAI, Elastic effects and phase segregation during the growth of thin alloy layers by molecular beam epitaxy, Phys. Rev. B, B56, 4955-4965 (1997).
  14. M. Laradji, A.-C. Shi, R.C. DESAI and J. Noolandi, On the Stability of Ordered Phases in Diblock Copolymer Systems, Macromolecules, 30, 3242-3255 (1997).
  15. M. Laradji, A.-C. Shi, R.C. DESAI and J. Noolandi, Stability of Ordered Phases in Weakly Segregated Diblock Copolymer Systems, Phys. Rev. Letters, 78, 2577-2580 (1997).
  16. F. Léonard and R.C. DESAI, Chemical Ordering During Surface Growth, Phys. Rev. B, B55, 9990-9998 (1997).
  17. F. Léonard, M. Laradji and R.C. DESAI, Molecular Beam Epitaxy in the Presence of Phase Separation, Phys. Rev. B, B55, 1887-1894 (1997).
  18. F. Léonard, M. Laradji and R.C. DESAI, Phase Separation in Heteroepitaxial Thin Film Growth, Physica A, A239, 129-136 (1997).
  19. O. Schönborn and R.C. DESAI, Phase-Ordering Kinetics on Curved Surfaces, Physica A, A239, 412-419 (1997).
  20. A.-C. Shi, J. Noolandi and R.C. DESAI, Theory of Anisotropic Fluctuations in Ordered Block Copolymer Phases, Macromolecules, 29, 6487-6504 (1996).
  21. C. Yeung, M. Rao and R.C. DESAI, Bounds on the Decay of the Autocorrelation in Phase Ordering Systems, Phys. Rev. E, E53, 3073-3077 (1996).
  22. C. Yeung, A.-C. Shi, J. Noolandi and R.C. DESAI, Stability and fluctuations in ordered copolymer phases, Macromolecular Theory and Simulations, 5, 291-298 (1996).
  23. C. Sagui and R.C. DESAI, Effects of Long Range Interactions on Ostwald Ripening, Phys. Rev. E, E52, 2822-2840 (1995).
  24. C. Sagui and R.C. DESAI, Late-Stage Kinetics of Systems with Competing Interactions Quenched into the Hexagonal Phase, Phys. Rev. E, E52, 2807-2821 (1995).
  25. S. Puri, R.C. DESAI and R. Kapral, Collision Dynamics of Fronts in the Korteweg- de Vries- Burgers Equation, Physica D, 89, 15-27 (1995).
  26. C. Sagui and R.C. DESAI, Ostwald Ripening in Systems with Competing Interactions, Phys. Rev. Letters, 74, 1119-1122 (1995).
  27. C. Sagui, A.M. Somoza and R.C. DESAI, Spinodal Decomposition in an Order-Disorder Phase Transition with Elastic Fields, Phys. Rev. E, E50, 4865-4879 (1994).
  28. C. Yeung, M. Rao and R.C. DESAI, Temporal Fluctuations and Hurst Exponents of Goldstone and Massive Modes, Phys. Rev. Letters , 73, 1813-1816 (1994).
  29. O. Schönborn, R.C. DESAI and D. Stauffer, Diffusion Under Nonlinear Bias and the Convective Fisher Equation, J. Phys. Letters, 27, L251-L255 (1994).
  30. O. Schönborn, S. Puri and R.C. DESAI, A Singular Perturbation Theory Analysis for Unstable Systems with Convective Nonlinearity, Phys. Rev. E, E49, 3480-3483 (1994).
  31. C. Yeung, R.C. DESAI, A.-C. Shi and J. Noolandi, Lower Critical Solution Temperature in Diblock Copolymer Melts, Phys. Rev. Letters, 72, 1834-1837 (1994).
  32. C. Sagui and R.C. DESAI, Kinetics of Phase Separation in Two Dimensional Systems with Competing Interactions, Phys. Rev. E, E49, 2225-2244 (1994).
  33. C. Yeung and R.C. DESAI, Pattern Formation in Laser Induced Melting, Phys. Rev. E, E49, 2096-2114 (1994).
  34. C. Sagui, A.M. Somoza, C. Roland and R.C. DESAI, Phase Separation in the Presence of a Surface: Ordering of a Surface Layer, J. Phys. Letters, 26, L1163-L1168 (1993).
  35. C. Sagui and R.C. DESAI, Kinetics of Topological Defects in Systems with Competing Interactions, Phys. Rev. Letters, 71, 3995-3998 (1993).
  36. C.M. Knobler and R.C. DESAI, Phase Transitions in Monolayers, Annual Reviews of Physical Chemistry, 43, 207-236 (1992), an invited review.

Recent Members of the Research Group

Department of Physics, 60 St. George St., Toronto, Ontario, M5S 1A7, Canada
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