110 research outputs found
Phase Transition in Strongly Degenerate Hydrogen Plasma
Direct fermionic path-integral Monte-Carlo simulations of strongly coupled
hydrogen are presented. Our results show evidence for the hypothetical plasma
phase transition. Its most remarkable manifestation is the appearance of
metallic droplets which are predicted to be crucial for the electrical
conductivity allowing to explain the rapid increase observed in recent shock
compression measurments.Comment: 1 LaTeX file using jetpl.cls (included), 5 ps figures. Manuscript
submitted to JETP Letter
Hole crystallization in semiconductors
When electrons in a solid are excited to a higher energy band they leave
behind a vacancy (hole) in the original band which behaves like a positively
charged particle. Here we predict that holes can spontaneously order into a
regular lattice in semiconductors with sufficiently flat valence bands. The
critical hole to electron effective mass ratio required for this phase
transition is found to be of the order of 80.Comment: accepted for publication in J. Phys. A: Math. Ge
Influence of the nature of confinement on the melting of Wigner molecules in quantum dots
We analyze the quantum melting of two-dimensional Wigner molecules (WM) in
confined geometries with distinct symmetries and compare it with corresponding
thermal melting. Our findings unfold complementary mechanisms that drive the
quantum and thermal crossovers in a WM and show that the symmetry of the
confinement plays no significant role in determining the quantum crossover
scale . This is because the zero-point motion screens the boundary effects
within short distances. The phase diagram as a function of thermal and quantum
fluctuations determined from independent criteria is unique, and shows
"melting" from the WM to both the classical and quantum "liquids." An
intriguing signature of weakening liquidity with increasing temperature, ,
is found in the extreme quantum regime. The crossover is associated with
production of defects. However, these defects appear to play distinct roles in
driving the quantum and thermal "melting." Our study will help comprehending
melting in a variety of experimental traps - from quantum dots to complex
plasma.Comment: 14 pages, 9 figure
Effective interaction potential and superfluid-solid transition of spatially indirect excitons
Using an adiabatic approximation we derive an effective interaction
potentially for spatially indirect excitons. Using this potential and path
integral Monte Carlo simulations we study exciton crystllization and the
quantum melting phase transition in a macroscopic system of 2D excitons.
Furthermore, the superfluid fraction is calculated as a function of density and
shown to vanish upon crystallization. We show that the commonly used dipole
model fails to correctly describe indirect excitons in quantum well structures
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