Finite-temperature phase diagram and critical point of the Aubry pinned-sliding transition in a two-dimensional monolayer
Articolo
Data di Pubblicazione:
2017
Citazione:
Finite-temperature phase diagram and critical point of the Aubry pinned-sliding transition in a two-dimensional monolayer / D. Mandelli, A. Vanossi, N. Manini, E. Tosatti. - In: PHYSICAL REVIEW. B. - ISSN 2469-9950. - 95:24(2017), pp. 245403.1-245403.8. [10.1103/PhysRevB.95.245403]
Abstract:
The Aubry unpinned-pinned transition in the sliding of two incommensurate lattices occurs for increasing mutual interaction strength in one dimension and is of second order at T = 0, turning into a crossover at nonzero temperatures. Yet, real incommensurate lattices come into contact in two dimensions, at finite temperature, generally developing a mutual Novaco-McTague misalignment, conditions in which the existence of a sharp transition is not clear. Using a model inspired by colloid monolayers in an optical lattice as a test two-dimensional (2D) case, simulations show a sharp Aubry transition between an unpinned and a pinned phase as a function of corrugation. Unlike one dimension, the 2D transition is now of first order, and, importantly, remains well defined at T > 0. It is heavily structural, with a local rotation of moire pattern domains from the nonzero initial Novaco-McTague equilibrium angle to nearly zero. In the temperature (T)-corrugation strength plane, the thermodynamical coexistence line between the unpinned and the pinned phases is strongly oblique, showing that the former has the largest entropy. This first-order Aubry line terminates with a novel critical point T = T-c, marked by a susceptibility peak. The expected static sliding friction upswing between the unpinned and the pinned phase decreases and disappears upon heating from T = 0 to T = T-c. The experimental pursuit of this novel scenario is proposed.
Tipologia IRIS:
01 - Articolo su periodico
Keywords:
Condensed Matter Physics
Elenco autori:
D. Mandelli, A. Vanossi, N. Manini, E. Tosatti
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