André Thiaville

Affilations

• Laboratoire de Physique des Solides, Université Paris-Sud & CNRS, Orsay, France

Title

Chiral magnetic textures: The viewpoint of micromagnetics

Abstract

The framework to describe the statics and dynamics of magnetic textures is called micromagnetics, meaning that it handles the local "micromagnetizations" whose sum is the magnetization of the whole sample, the observable of a magnetometry experiment. In fact, since this model was formalized by W. F. Brown in the 40’s, magnetic microscopy techniques have greatly developed and now provide high resolution images (in space and in time) of the magnetic textures. Strikingly enough, micromagnetics is still very accurate to describe the physics of magnetics textures, with just a few parameters. The chiral magnetic textures are the last field where experiments and micromagnetic predictions, once the relevant energy term has been included, have been compared. After introducing standard micromagnetics, the incorporation of the antisymmetric exchange of Dzyaloshinskii-Moriya (DMI) will be detailed. The emphasis will be put on ultrathin magnetic films in a structurally asymmetric architecture, where the so-called interfacial DMI occurs. A series of consequences of the presence of this interaction will be described, including the impact on the structure of the magnetic domain walls and the consequences on their dynamics, the possible destabilization of the uniform state, the stabilization of so-called magnetic skyrmions, the induction of specific edge effects, the modification of spin-wave modes. A common theme in all these examples will be the estimation, from the experimental results, of the parameter characterizing the DMI strength. This experimental input is vital for the microscopic modeling of interfacial DMI, with the goal to eventually control the DMI by the architecture of the sample.