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arXiv · 1302.2319

Skyrmions with varying size and helicity in composition-spread helimagnetic alloys

K. Shibata·X. Z. Yu·T. Hara·D. Morikawa·N. Kanazawa·K. Kimoto·S. Ishiwata·Y. Matsui·Y. Tokura
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Abstract

The chirality, i.e. left or right handedness, is an important notion in a broad range of science. In condensed matter, this occurs not only in molecular or crystal forms but also in magnetic structures. A magnetic skyrmion, a topologically-stable spin vortex structure, as observed in chiral-lattice helimagnets is one such example; the spin swirling direction (skyrmion helicity) should be closely related to the underlying lattice chirality via the relativistic spin-orbit coupling (SOC). Here, we report on the correlation between skyrmion helicity and crystal chirality as observed by Lorentz transmission electron microscopy (TEM) and convergent-beam electron diffraction (CBED) on the composition-spread alloys of helimagnets Mn1-xFexGe over a broad range (x = 0.3 - 1.0) of the composition. The skyrmion lattice constant or the skyrmion size shows non-monotonous variation with the composition x, accompanying a divergent behavior around x = 0.8, where the correlation between magnetic helicity and crystal chirality is reversed. The underlying mechanism is a continuous x-variation of the SOC strength accompanying sign reversal in the metallic alloys. This may offer a promising way to tune the skyrmion size and helicity.

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K. Shibata, X. Z. Yu, T. Hara, D. Morikawa, N. Kanazawa, K. Kimoto, S. Ishiwata, Y. Matsui, Y. Tokura. 2013-02-10. Skyrmions with varying size and helicity in composition-spread helimagnetic alloys. https://doi.org/10.1038/nnano.2013.174

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