12月 11（木） 16:00～

発表者

Martin Luc Rosinberg (所属：LPTMC, Universite Pierre et Marie Curie)

題目

Hysteresis and complexity in externally driven glassy systems

概要

 
Rate-independent hysteresis is universally observed in disordered systems
driven by an external field at low temperature, such as random magnets, 
glasses, plastic and ferro-elastic materials, etc...These systems are 
characterized by a complex energy landscape with an exponentially large 
number of metastable states, which is also responsible for the discontinuous, 
jerky response to the external force (Barkausen noise, acoustic emission, 
etc...). A prototype of this behaviour is the out-ofequilibrium Random Field 
Ising Model (RFIM) at zero temperature, which has been extensively studied in 
recent years, following the seminal work of Sethna et al [1].
However, the precise relationship between hysteresis and metastability is still 
not well understood and several theoretically and experimentally important 
questions are not well answered. In this framework, we shall discuss two
closely related issues: 
i) the characterization of the hysteresis loop as a special path among the 
metastable states [2] : is it the envelope of the region where the number 
of typical metastable states is exponential ? 
(ii) the influence of the driving protocol on the shape of the loop [3] : 
what happens when one controls the conjugated extensive variable - or its 
time derivative - instead of the field ? 
Why is a re-entrant loop usually observed ?

[1] J. P. Sethna, K. Dahmen, S. Kartha, J. A. Krumhansl, B. W. Roberts, 
and J. D. Shore, Phys. Rev. Lett. 70, 3347 (1993).

[2] F. Detcheverry, M.L. Rosinberg, and G. Tarjus, Eur. Phys. J. B 44, 327 (2005); 
F. J. Perez-Reche, M. L. Rosinberg, and G. Tarjus G, Phys. Rev. B 77, 064422 (2008);
 M.L. Rosinberg, G. Tarjus, and F. J. Perez-Reche, J. Stat. Mech , P10004
(2008) ; M.L. Rosinberg, G. Tarjus, and F. J. Perez-Reche, preprint cond-mat/0809.3774.

[3] X. Illa, M.L. Rosinberg, and E. Vives, Phys. Rev. B 74, 224403 (2006). 

      

場所

京都大学 基礎物理学研究所 研究棟・講義室K102

地図 (Map)