Archimedean screw in driven chiral magnets - Kölner UniversitätsPublikationsServer

del Ser, Nina, Heinen, Lukas and Rosch, Achim ORCID: 0000-0002-6586-5721 (2021). Archimedean screw in driven chiral magnets. SciPost Phys., 11 (1). AMSTERDAM: SCIPOST FOUNDATION. ISSN 2542-4653

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DOI:10.21468/SciPostPhys.11.1.009

Abstract

In chiral magnets a magnetic helix forms where the magnetization winds around a propagation vector q. We show theoretically that a magnetic field B-perpendicular to(t) perpendicular to q, which is spatially homogeneous but oscillating in time, induces a net rotation of the texture around q. This rotation is reminiscent of the motion of an Archimedean screw and is equivalent to a translation with velocity nu(screw) parallel to q. Due to the coupling to a Goldstone mode, this non-linear effect arises for arbitrarily weak B-perpendicular to(t) with nu(screw) proportional to vertical bar B-perpendicular to vertical bar(2) as long as pinning by disorder is absent. The effect is resonantly enhanced when internal modes of the helix are excited and the sign of nu(screw) can be controlled either by changing the frequency or the polarization of B-perpendicular to(t). The Archimedean screw can be used to transport spin and charge and thus the screwing motion is predicted to induce a voltage parallel to q. Using a combination of numerics and Floquet spin wave theory, we show that the helix becomes unstable upon increasing B-perpendicular to, forming a 'time quasicrystal' which oscillates in space and time for moderately strong drive.

Item Type:

Journal Article

Creators:

Creators	Email	ORCID	ORCID Put Code
del Ser, Nina	UNSPECIFIED	UNSPECIFIED	UNSPECIFIED
Heinen, Lukas	UNSPECIFIED	UNSPECIFIED	UNSPECIFIED
Rosch, Achim	UNSPECIFIED	orcid.org/0000-0002-6586-5721	UNSPECIFIED