Structural transition in two-dimensional Hertzian spheres in the presence of random pinning.

Tsiok, E N; Fomin, Yu D; Gaiduk, E A; Ryzhov, V N · Phys Rev E · 2021

basic_science · Level V

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Abstract

Using molecular dynamics simulation we have investigated the influence of random pinning on the phase diagram and melting scenarios of a two-dimensional system with the Hertz potential for α=5/2. It has been shown that random pinning can cardinally change the mechanism of first-order transition between the different crystalline phases (triangular and square) by virtue of generating hexatic and tetratic phases: a triangular crystal to hexatic transition is of the continuous Berezinskii-Kosterlitz-Thouless (BKT) type, a hexatic to tetratic transition is of first order, and finally, there is a continuous BKT-type transition from tetratic to the square crystal.