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Phase transitions in thin films with competing surface fields and gradients
Lijun Pang1, D P Landau, K Binder
1Center for Simulational Physics, Department of Physics and Astronomy, The University of Georgia, Athens, Georgia 30602-2451, USA.
Physical Review. E, Statistical, Nonlinear, and Soft Matter Physics
|December 21, 2011
Summary
This study explores phase equilibria in thin films using Ising-lattice gas models. It reveals how competing surface fields and gradients influence domain structures and phase transitions.
Area of Science:
- Statistical Mechanics
- Condensed Matter Physics
- Materials Science
Background:
- Phase equilibria in confined systems are crucial for understanding material properties.
- Thin-film geometries present unique challenges and phenomena due to confinement effects.
- Competing fields can lead to complex domain structures and phase transitions.
Purpose of the Study:
- To investigate phase equilibria in an Ising-lattice gas model under confinement in a thin-film geometry.
- To analyze the influence of competing surface fields and a field gradient on domain formation and phase transitions.
- To compare results from Monte Carlo simulations and phenomenological theory.
Main Methods:
- Monte Carlo simulations were employed to model the Ising-lattice gas system.
- A phenomenological theory was developed to complement the simulation results.
- An L×L×D geometry with competing surface fields and a z-direction field gradient was utilized.
Main Results:
- Phase coexistence between oppositely oriented domains occurs for small field gradients (g).
- A second-order transition to a monodomain state is observed for weak gradients.
- The transition becomes first-order above a tricritical threshold, and large gradients stabilize antiparallel domain states.
Conclusions:
- The interplay between surface fields and gradients dictates the emergent domain structures and phase transition orders.
- The study provides insights into the fundamental physics of phase equilibria in confined systems.
- Both simulation and theory confirm the complex behavior of the Ising-lattice gas model under competing fields.
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