Thermodynamics of a continuous medium with electric and magnetic dipoles

Abstract

The thermodynamics of an electrically charged, multicomponent fluid with spontaneous electric and magnetic dipoles is analysed in the presence of electromagnetic fields. Taking into account the chemical composition of the current densities and stress tensors leads to three types of irreversible terms: scalars, vectors and pseudo-vectors. The scalar terms account for chemical reactivities, the vectorial terms account for transport and the pseudo-vectorial terms account for relaxation. The linear phenomenological relations, derived from the irreversible evolution, describe notably the Lehmann and electric Lehmann effects, the Debye relaxation of polar molecules and the Landau-Lifshitz relaxation of the magnetisation. This formalism accounts for the thermal and electric magnetisation accumulations and magnetisation waves. It also predicts that a temperature gradient affects the dynamics of magnetic vortices and drives magnetisation waves.PACS. 05.70. Ln, 75.76.+j,

Magnetic Contribution to the Seebeck Effect

“…It constitutes a framework within which to define a variety of spintronics effects [ 46 ]. Here, we make use of an earlier development in which we had treated the magnetic induction field as a state variable [ 34 ]. Thanks to this development, an additional term had been found in the generalized force associated with the matter current density.…”

“…When electromagnetic fields are treated as state variables [ 34 ], the entropy source density contains a term of the form where designates either the vectorial entropy current density, or the current density of the substances A , B , … i.e., . Here, we will consider two substances only, labelled A and B .…”

“…In Reference [ 34 ], we showed that in a metallic ferromagnet, in the absence of convection, intrinsic rotations and electric dipoles, is given by where is the electrochemical potential of substance B , with the charge per mole of B , V the electrostatic potential, the magnetization, and the magnetic induction field. The notation is to be understood as, e.g., .…”

Evidence for a Magnetic Seebeck Effect

“…The interplay of spin, charge and heat transport defines the rich field known as spin caloritronics [4]. Prompted by these recent developments, we established a formalism describing the irreversible thermodynamics of a continuous medium with magnetisation [5].…”

Dynamics of field-induced phases in spin-1 antifferomagnetic chains

“…This was tested on a yttrium iron garnet (YIG) thin crystals, a compound that is known to be a ferrimagnetic insulator [207]. We should emphasize that the underlying physics of the magnetic Seebeck effect in a ferrimagnet is formulated using an alternative framework [216]. In this case, the lattice sites carry a magnetic dipole m A and if a constant external magnetic field H ext and a temperature gradient Using the appropriate experimental procedure it is possible that the magnetic Seebeck effect can be observed using one-dimensional S = 1/2 Heisenberg chains as an electric insulator.…”