Berry curvature and dynamics of a magnetic bubble

Abstract

Magnetic bubbles have been the subject of intensive studies aiming to investigate their applications to memory devices. A bubble can be regarded as the closed domain wall and is characterized by the winding number of the in-plane components or the skyrmion number Nsk, which are related to the number of Bloch lines (BLs). For the magnetic bubbles without BLs, the Thiele equation assuming no internal distortion describes the center-of-mass motion of the bubbles very well. For the magnetic bubbles with BLs, on the other hand, their dynamics is affected seriously by that of BLs along the domain wall. Here we show theoretically, that the distribution of the Berry curvature bz, i.e., the solid angle formed by the magnetization vectors, in the bubble plays the key role in the dynamics of a bubble with in a dipolar magnet. In this case, the integral of bz over the space is zero, while the nonuniform distribution of bz and associated Magnus force induce several nontrivial coupled dynamics of the internal deformation and center-of-mass motion as explicitly demonstrated by numerical simulations of Landau–Lifshitz-Gilbert equation. These findings give an alternative view and will pave a new route to design the bubble dynamics.