Vibrations and transitions across barrier of strained nanoribbons at finite temperature

Hanakata, Paul Z. ; Bhabesh, Sourav S. ; Yllanes, David ; Nelson, David R. ; Bowick, Mark J.

Resumen: Crystalline sheets (e.g., graphene and transition metal dichalcogenides) liberated from a substrate are a paradigm for materials at criticality, because flexural phonons can fluctuate into the third dimension. Although studies of static critical behaviors (e.g., the scale-dependent elastic constants) are plentiful, investigations of dynamics remain limited. Here, we use molecular dynamics to study the time dependence of the midpoint (the height center of mass) of doubly clamped nanoribbons, as prototypical graphene resonators, under a wide range of temperature and strain conditions. By treating the ribbon midpoint as a Brownian particle confined to a nonlinear potential (which assumes a double-well shape beyond the buckling transition), we formulate an effective theory describing the ribbon's transition rate across the two wells and its oscillations inside a given well. We find that, for nanoribbbons compressed above the Euler buckling point and thermalized above a temperature at which the nonlinear effects due to thermal fluctuations become significant, the exponential term (the ratio between energy barrier and temperature) depends only on the geometry but not the temperature, unlike the usual Arrhenius behavior. Moreover, we find that the natural oscillation time for small strain shows a nontrivial scaling o∼ 0⁢−/4, with 0 being the ribbon length, =2−/2 being the dynamic critical exponent, =0.8 being the scaling exponent describing scale-dependent elastic constants, and being the temperature. These unusual scale- and temperature-dependent dynamics thus exhibit dynamic criticality and could be exploited in the development of graphene-based nanoactuators.

Idioma: Inglés

DOI: 10.1103/PhysRevMaterials.8.016001

Año: 2024

Publicado en: PHYSICAL REVIEW MATERIALS 8, 1 (2024), 016001 [14 pp.]
ISSN: 2475-9953

Factor impacto JCR: 3.4 (2024)

Categ. JCR: MATERIALS SCIENCE, MULTIDISCIPLINARY rank: 224 / 460 = 0.487 (2024) - Q2 - T2

Factor impacto SCIMAGO: 0.945 - Physics and Astronomy (miscellaneous) (Q1) - Materials Science (miscellaneous) (Q1)

Financiación: info:eu-repo/grantAgreement/ES/MINECO-AEI-FEDER/PGC2018-094684-B-C21

Tipo y forma: Artículo (PostPrint)