부산대학교 도서관

Since in the non-equilibrium state the distributed intrinsic angularmomentum of a material medium (i.e., that due to the internal degrees offreedom of the constitutent molecules) is not necessarily a function of themagnetic moment density, it is necessary to include it explicitly in theequations of irreversible thermodynamics. It is an extensive variablecontributing to the specific internal energy increment over and above theusual electromagnetic term $({\bf E}\cdot d{\bf D}+{\bf H}\cdot d{\bfB})/\rho$. This gives rise to an additional term in the entropy production.As a consequence of the formalism here developed, magnetic relaxation,whenever a phenomenological description is possible, can be derived fromirreversible thermodynamics. The phenomenological equation for the timerate of change of the intrinsic angular momentum density is ageneralization of the Bloch equation of nuclear induction. Noting that inirreversible thermodynamics, irreversible processes are associated withconservation laws, the more general meaning of this work is that``thermodynamics of irreversible processes is completed by the fact that acharacteristic irreversible process is now associated also with theconservation law of angular momentum''.