Symmetry Theory of the Flexomagnetoelectric Effect in the Bloch Lines

TL;DR

This paper classifies the symmetry groups of Bloch lines, proposes methods for their experimental study, and introduces a new magnetoelectric memory concept based on Bloch lines with potential applications near the Curie temperature.

Contribution

It provides a comprehensive symmetry classification of Bloch lines and introduces experimental methods and a novel magnetoelectric memory device utilizing these lines.

Findings

48 magnetic point groups of Bloch lines identified

A tip electrode method for creating Bloch lines proposed

A new flexomagnetoelectric coupling near Curie temperature discovered

Abstract

It was shown, that there are 48 magnetic point groups of the Bloch lines including 22 (11 time-invariant and 11 time-noninvariant) enantimorphic and 26 non-enantiomorphic groups. The Bloch lines with the time-noninvariant enantiomorphism have identical types (parities) of the magnetization and polarization dependences. The soliton like Bloch lines are derived from the symmetry classification. The tip electrode method of the creation of these Bloch lines is suggested for the potential applications in the magnetoelectric memory devices. The method of the experimental determination of the flexomagnetoelectric properties of the Bloch lines carried by the Bloch domain walls has been suggested. New type of the flexomagnetoelectric coupling, determined by the spatial derivatives of the electric polarization can be found in the vicinity of the Curie temperature or compensation point of the ferrimagnets. The multiple states Bloch line based magnetoelectric/multiferroic memory is proposed. It can be considered as a concept of the magnetoelectric enhancement of existing Bloch line memory invention.