Higher-order relaxation magnetic phenomena and a hierarchy of first-order relaxation variables

Autori

  • David Jou Universitat Autònoma de Barcelona, Departament de F.sica, Grup de F.sica Estadistica, 08193 Bellaterra, Catalonia, Spain
  • Liliana Restuccia Università degli Studi di Messina Dipartimento di Scienze Matematiche e Informatiche, Scienze Fisiche e Scienze della Terra Viale F.S. D’Alcontres, 31, 98166 Messina, Italy

DOI:

https://doi.org/10.1478/AAPP.97S2A10

Abstract

In previous papers one of us (LR) has studied thermodynamic theories for magnetic relaxation phenomena due to several internal variables. In particular, she has obtained equations involving time derivatives of the magnetic field B up to the n-th order, and time derivatives of the magnetization M up to (n + 1)-th order. Such kind of equations generalize other kinds of physical phenomena, such as stresses τ as a function of small strains ε, and electrical polarizations P as a function of the electric field E. The aim of the present work is to provide a particular illustration of the theory, relating the mentioned n-th order relaxation equation to a hierarchy of first-order relaxation equations. Though this is only a simple situation, it may be helpful to relate the general equation to the microscopic structure of the system. Furthermore, we study in detail the form of the entropy and its consequences on the hierarchy of relaxation equations.

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Pubblicato

2019-12-20

Fascicolo

Vol 97, SUPPL NO 2 (2019): NACS 2017

Sezione

NACS 2017 (Conference Proceedings)

Licenza

Creative Commons License
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