Effect of disorder on phases across two-dimensional thermal melting

P Jami and P Chaudhuri and C Dasgupta and A Ghosal, PHYSICAL REVIEW E, 109, L062101 (2024).

DOI: 10.1103/PhysRevE.109.L062101

We study melting in a two-dimensional system of classical particles with Gaussian -core interactions in disordered environments. The pure system validates the conventional two-step melting with a hexatic phase intervening between the solid and the liquid. This picture is modified in the presence of pinning impurities. A random distribution of pinning centers forces a hexaticlike low -temperature phase that transits into a liquid at a single melting temperature T (m) (RP) . In contrast, pinning centers located at randomly chosen sites of a perfect crystal anchor a solid at low temperatures which undergoes a direct transition to the liquid at T (m) (CP) . Thus, the two-step melting is lost in either case of disorder. We discuss the characteristics of melting depending on the nature of the impurities.

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