Transition of a 2D crystal to a non-equilibrium two-phase coexistence state

• Published in: Physics of plasmas 2023-04, Vol.30 (4)
• Main Authors: Singh, Swarnima, Bandyopadhyay, P., Kumar, Krishan, Hariprasad, M. G., Arumugam, S., Sen, A.
• Format: Article
• Language: English
• Subjects: Argon plasma; Dusty plasmas; Glow discharges; Liquid phases; Monolayers; Plasma physics; Surface tension
• ISSN: 1070-664X; 1089-7674
• DOI: 10.1063/5.0139228

In this paper, we present experimental observation of the transition of a 2D dust crystal to a non-equilibrium solid–liquid phase coexistence state. The experiments have been carried out in an L-shaped dusty plasma experimental device in a DC glow discharge argon plasma environment. Initially, a monolayer crystalline structure is formed, which is later transformed to a two-phase coexistence state using the background neutral pressure as a control parameter. Self-excited horizontal oscillations are found in the center of the monolayer prior to the appearance of the coexistence state. It is observed that a molten center coexists with a solid periphery. Various structural, thermodynamic, and dynamical quantities are used to characterize the phase state. The surface tension at the solid–liquid circular interface is also determined. A detailed parametric study is made to delineate the existence region of such a state. It is found that melting caused at the core is due to the onset of a localized Schweigert instability in the presence of a few stray particles beneath the top layer in that region.