Event

Physics Seminar: Seeking a well-defined local temperature for nanoscale fluctuations

  • Speaker  Professor Ralph V. Chamberlin, invited by Prof. Dr. Massimiliano ESPOSITO

  • Location

    Campus Limpertsberg, Bâtiment des Sciences, BS 0.03

    LU

  • Topic(s)
    Physics & Materials Science

Seeking a well-defined local temperature for nanoscale fluctuations

Abstract:

Temperature (T) should provide a unifying concept for all scientific research methods on size scales from atoms to bulk behavior. However, we find inconsistencies in the local T deduced from experiments, theory, and computer simulations. For example, measurements of specific heat show heterogeneous values of local T that persistently deviate from the homogeneous T* required for standard thermodynamics. Furthermore, equilibrium MD simulations show energy fluctuations that exceed usual fluctuation relations based on Boltzmann’s factor, sometimes by more than a factor of fifty. Any viable definition of local T must include all sources of energy, even those that arise on the scale of nanometers, as fully formulated only in the theory of small-system thermodynamics. This nanothermodynamics is based on two basic principles: that small systems can be treated self-consistently by coupling them to an ensemble of similarly small systems, and that a large ensemble of small systems should behave like a large system. I plan to discuss various applications of nanothermodynamics, including a novel solution to Gibbs’ paradox and an Ising model with orthogonal constraints for 1/f-like noise.

About the speaker:

Ralph Chamberlin joined Arizona State University in 1986. He studies the thermal and dynamic properties of materials. His career has shifted between experiments, theory, and computer simulations. He has been involved in developing and interpreting stretched-exponential relaxation for spin glasses, non-resonant spectral hole burning for supercooled liquids, and nanothermodynamics for the thermal and dynamics properties of complex systems on the scale of nanometers. Practical applications of his research include characterizing and controlling excess thermal fluctuations (“hot spots”) in advanced materials, and a basic understanding of how nanometer-sized thermal fluctuations can cause bits of magnetic memory to forget their alignment.