Abstract
The topic of magnetic antidot lattice (MAL) arrays has drawn attention from both fundamental research as well as from application point of view. MAL arrays are promising candidates for making domain engineering in thin films. For various applications it is necessary to understand the magnetization reversal mechanism as well as the relaxation dynamics. In this context we have studied magnetic antidot lattice (MAL) arrays of Co/Pt with perpendicular anisotropy fabricated by combination of photolithography and sputtering deposition. Kerr microscopy domain imaging for the continuous thin film reveals the formation of typical bubble domains of perpendicular media with high anisotropy. However, presence of periodic holes in the MAL arrays lead to nucleation of localised smaller bubbles. We have performed simulations using object oriented micromagnetic framework (OOMMF) which reproduced the experimental results even considering antidot arrays in nano dimension. In literature it has been reported that in MAL arrays with in-plane anisotropy the domain propagation gets significantly hindered by the presence of the holes. However here we show that in perpendicularly magnetized Co/Pt the propagation of the domain walls is not restricted by the presence of the antidots. Further we have performed magnetic relaxation study and found that the global relaxation time for the MAL arrays of Co/Pt is faster as compared to it’s parent thin film. This behavior is opposite to what has been observed in literature for in-plane magnetized MAL arrays.
Highlights
Fast switching of the magnetization in thin films and nanostructures is of utmost importance in high frequency inductors, microwave filters, spin valve, MRAM based devices, etc.[1,2]
We report the investigation of magnetic domains and relaxation by state-of-art magneto-optic Kerr effect (MOKE) based microscopy in micro-dimensional magnetic antidot lattice (MAL) arrays of Co/Pt with perpendicular magnetic anisotropy (PMA)
We demonstrate by simulation using object oriented micro magnetic framework (OOMMF) that the experimental observations can be reproduced and extended for MAL arrays consisting of holes with dimensions of few tens of nanometre
Summary
Fast switching of the magnetization in thin films and nanostructures is of utmost importance in high frequency inductors, microwave filters, spin valve, MRAM based devices, etc.[1,2]. Most of the works on the MALs so far have been focused on the in-plane magnetized systems where the lateral movement of the domain walls are engineered by incorporating the periodic holes[6,7,8,9]. This magnetic hardening is usually accompanied by slower relaxation time in case of the MAL arrays[10] The latter is not desirable for storage applications where rapid reversal of the spins is essential in reading and writing information[2,14]. We report the investigation of magnetic domains and relaxation by state-of-art magneto-optic Kerr effect (MOKE) based microscopy in micro-dimensional MAL arrays of Co/Pt with PMA. We discuss the relaxation behavior for the MAL arrays of PMA based Co/Pt to their counterpart with in-plane magnetic anisotropy reported in literature
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