Real-space determination of the isolated magnetic skyrmion deformation under electric current flow
Fehmi Sami Yasin, Jan Masell, Kosuke Karube, Akiko Kikkawa, Y. Taguchi, Yoshinori Tokura, Xiuzhen Yu
Abstract
The manipulation and control of electron spins, the fundamental building blocks of magnetic domains and spin textures, are at the core of spintronics. Of particular interest is the effect of the electric current on topological magnetic skyrmions, such as the current-induced deformation of isolated skyrmions. The deformation has consequences ranging from perturbed dynamics to modified packing configurations. In this study, we measured the current-driven real-space deformation of isolated, pinned skyrmions within Co 10 Zn 10 at room temperature. We observed that the skyrmions are surprisingly soft, readily deforming during electric current application into an elliptical shape with a well-defined deformation axis (semimajor axis). We found that this axis rotates unidirectionally toward the current direction irrespective of electric current polarity and that the elliptical deformation reverses back upon current termination. We quantified the average distortion δ, which increased by ∼90% during the largest applied current density | j | = 8.46 ×10 9 A/m 2 when compared with the skyrmion’s intrinsic shape ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"> <mml:mi>j</mml:mi> <mml:mo>=</mml:mo> <mml:mn>0</mml:mn> </mml:math> ). Additionally, we demonstrated an approximately 120% average skyrmion core size expansion during current application, highlighting the skyrmions’ inherent topological protection. This evaluation of in situ electric current–induced skyrmion deformation paints a clearer picture of spin-polarized electron–skyrmion interactions and may prove essential in designing spintronic devices.