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Colloquium Event

Applied Physics/Physics Colloquium: David Nelson - "Scale-dependent Elastic Constants in Mutilated Sheets and Shells"

Date
Tue November 19th 2024, 3:30pm
Event Sponsor
Applied Physics/Physics Colloquium
Department of Physics
Location
Hewlett Teaching Center
370 Jane Stanford Way, Stanford, CA 94305
201

Understanding deformations of macroscopic thin plates and shells has a long and rich history, culminating with the nonlinear Foeppl-von Karman equations in 1904.  However, thermal fluctuations in thin elastic membranes fundamentally alter the long wavelength physics, leading to strongly scale-dependent elastic constants, consistent with experiments that twist and bend atomically-thin free-standing graphene sheets.  With thermally excited graphene sheets, one can study as well the quantum mechanics of two dimensional Dirac massless fermions in a fluctuating curved space whose dynamics resembles a simplified form of general relativity.  We also describe recent measurements of a scale-dependent bending rigidity for rippled nanometer-thick cantilevers of Al_2O_3.     We then move on to analyze the physics of sheets mutilated with puckers and stitches.   Puckers and stitches lead to Ising-like phase transitions that strongly affect the physics of the fluctuating sheet.  Thermal fluctuations also cause thin spherical shells beyond a certain critical radius to spontaneously collapse.