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Melting and Reentrant Freezing of Two-Dimensional Colloidal Crystals in Confined Geometry

1999; American Physical Society; Volume: 82; Issue: 16 Linguagem: Inglês

10.1103/physrevlett.82.3364

1092-0145

R. Bubeck, Clemens Bechinger, S. Neser, P. Leǐderer,

Theoretical and Computational Physics

We study the melting behavior of a finite number ( $N\ensuremath{\le}45$) of paramagnetic colloidal spheres in a two-dimensional circular hard wall cavity. The interaction strength between the particles is varied by applying a magnetic field $B$. At high $B$, i.e., strong interaction, the particles are arranged in a highly ordered shell-like structure. With decreasing $B$ we observe first a loss of angular order between adjacent shells. Upon further reduction of the external $B$ field, however, angular order is restored again before the system melts completely. We propose a simple mechanism to account for this reentrance phenomenon.