Electromagnetic Response Theory with Relativistic Corrections: Selfconsistency and Validity of Variables

Fuente: arXiv
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Main Author: Cho, Kikuo
Format: Preprint
Published: 2024
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author Cho, Kikuo
author_facet Cho, Kikuo
contents Schrödinger-Pauli equation (SP-eq) derived from weakly relativistic approximation (WRA) of Dirac eq, combined with Electromagnetic (EM) field Lagrangian for variational principle, is expected to give a new level of EM response theory. A complete process of this formulation within the second order WRA is given, with explicit forms of charge and current densities, $ρ, \vec{J}$, and electric and magnetic polarizations, $\vec{P}$, $\vec{M}$ containing correction terms. They fulfill, not only the continuity equation, but also the relations $\nabla \cdot \vec{P}=-ρ, \ \partial \vec{P}/\partial t + c \nabla \times \vec{M} = \vec{J}$, known in the classical EM theory for the corresponding macroscopic variables. This theory should be able to describe all the EM responses within the second order WRA, and the least necessary variables are ${ϕ, \vec{A}, ρ, \vec{J}}$ (six independent components). From this viewpoint, there emerges a problem about the use of "spin current" popularly discussed in spintronics, because it does not belong to the group of least necessary variables.
format Preprint
id arxiv_https___arxiv_org_abs_2407_09570
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Electromagnetic Response Theory with Relativistic Corrections: Selfconsistency and Validity of Variables
Cho, Kikuo
Classical Physics
Materials Science
Schrödinger-Pauli equation (SP-eq) derived from weakly relativistic approximation (WRA) of Dirac eq, combined with Electromagnetic (EM) field Lagrangian for variational principle, is expected to give a new level of EM response theory. A complete process of this formulation within the second order WRA is given, with explicit forms of charge and current densities, $ρ, \vec{J}$, and electric and magnetic polarizations, $\vec{P}$, $\vec{M}$ containing correction terms. They fulfill, not only the continuity equation, but also the relations $\nabla \cdot \vec{P}=-ρ, \ \partial \vec{P}/\partial t + c \nabla \times \vec{M} = \vec{J}$, known in the classical EM theory for the corresponding macroscopic variables. This theory should be able to describe all the EM responses within the second order WRA, and the least necessary variables are ${ϕ, \vec{A}, ρ, \vec{J}}$ (six independent components). From this viewpoint, there emerges a problem about the use of "spin current" popularly discussed in spintronics, because it does not belong to the group of least necessary variables.
title Electromagnetic Response Theory with Relativistic Corrections: Selfconsistency and Validity of Variables
topic Classical Physics
Materials Science
url https://arxiv.org/abs/2407.09570