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Random pinning changes the melting scenario of a two-dimensional core-softened potential system
E N Tsiok1, D E Dudalov1, Yu D Fomin1,2
1Institute for High Pressure Physics RAS, Kaluzhskoe shosse 14, 142190 Troitsk, Moscow, Russia.
Physical Review. E, Statistical, Nonlinear, and Soft Matter Physics
|October 15, 2015
Summary
Disordered two-dimensional systems exhibit altered melting behaviors. Random pinning transforms high-density first-order melting into two distinct transitions, impacting phase diagrams.
Area of Science:
- Condensed Matter Physics
- Materials Science
Background:
- Two-dimensional systems on solid substrates experience quenched disorder from defects.
- Substrate defects significantly influence system melting scenarios, complicating experimental interpretation.
Purpose of the Study:
- Investigate the effect of quenched disorder on the melting scenario of a two-dimensional system with a core-softened potential.
- Analyze how particle pinning, inducing disorder, modifies the system's phase transitions.
Main Methods:
- Molecular dynamics simulations were employed.
- A two-dimensional system with a core-softened potential and a fraction of pinned particles was simulated.
Main Results:
- At low densities, disorder causes a widening of the hexatic phase, consistent with known effects.
- At high densities, random pinning transforms the first-order melting transition into a continuous solid-hexatic transition followed by a first-order hexatic-isotropic liquid transition.
Conclusions:
- Quenched disorder fundamentally alters the melting behavior of two-dimensional systems, particularly at high densities.
- The findings necessitate careful consideration of substrate defects when interpreting experimental results of two-dimensional systems.
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