Programmability of Co-antidot lattices of optimized geometry

Tobias Schneider,Antje Oelschlägel,Mikhail P Kostylev,Jürgen Lindner,Andreas Neudert,Manuel Langer,Anna Semisalova,Rantej Bali,Jürgen Fassbender,Kilian Lenz,Adekunle O Adeyeye,Ewa Kowalska,Julia Alekhina,Kay Potzger

doi:10.1038/srep41157

Abstract

Programmability of stable magnetization configurations in a magnetic device is a highly desirable feature for a variety of applications, such as in magneto-transport and spin-wave logic. Periodic systems such as antidot lattices may exhibit programmability; however, to achieve multiple stable magnetization configurations the lattice geometry must be optimized. We consider the magnetization states in Co-antidot lattices of ≈50 nm thickness and ≈150 nm inter-antidot distance. Micromagnetic simulations were applied to investigate the magnetization states around individual antidots during the reversal process. The reversal processes predicted by micromagnetics were confirmed by experimental observations. Magnetization reversal in these antidots occurs via field driven transition between 3 elementary magnetization states – termed G, C and Q. These magnetization states can be described by vectors, and the reversal process proceeds via step-wise linear operations on these vector states. Rules governing the co-existence of the three magnetization states were empirically observed. It is shown that in an n × n antidot lattice, a variety of field switchable combinations of G, C and Q can occur, indicating programmability of the antidot lattices.

Highlights

Programmability of stable magnetization configurations in a magnetic device is a highly desirable feature for a variety of applications, such as in magneto-transport and spin-wave logic
Coercivities of the antidot lattice varied between 300 and 380 Oe depending on the direction of field w.r.t. the lattice symmetry, showing significant magnetic anisotropy induced by the antidot pattern
C and Q states were stabilized in the square rings even at zero applied field. This suggests that in the above antidot lattices, where we have shown that the C and Q states occur during the reversal process, it may be possible to stabilize these states in remanence as well

Summary

Introduction

Programmability of stable magnetization configurations in a magnetic device is a highly desirable feature for a variety of applications, such as in magneto-transport and spin-wave logic. Periodic systems such as antidot lattices may exhibit programmability; to achieve multiple stable magnetization configurations the lattice geometry must be optimized. The reversal processes predicted by micromagnetics were confirmed by experimental observations Magnetization reversal in these antidots occurs via field driven transition between 3 elementary magnetization states – termed G, C and Q. Spin-wave functionality can be dramatically enhanced in devices with programmable magnetization states7 In such experiments the collective behaviour of the antidots has been considered – the local variation of the magnetization around antidots, and their potential for programmability have rarely been taken into account. For instance it has been reported that www.nature.com/scientificreports/

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