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

EN Tsiok and YD Fomin and EA Gaiduk and VN Ryzhov, PHYSICAL REVIEW E, 103, 062612 (2021).

DOI: 10.1103/PhysRevE.103.062612

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 alpha = 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.

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