Lattice symmetry and magnetization reversal in micron-size antidot arrays in Permalloy film

Abstract

The magnetization reversal in four arrays of micron-size circular holes ͑antidots͒ in a Permalloy film has been studied by means of quantitative magneto-optic Kerr vector magnetometry and magnetic force microscopy. The primitive antidot meshes of the arrays investigated here can be classified as square, rectangular, hexagonal, and oblique. The vector magnetometry data show that the hole arrays induce a magnetic anisotropy completely different from that of the unpatterned film, with new hard axes along the directions connecting nearest neighboring holes. Also the coercive field is strongly affected by the pattern. The results of the vector magnetometry analysis indicate that the reversal process takes place through a collective and periodic domain nucleation and expansion process. The domain structure in the remanent state has been investigated by magnetic force microscopy imaging. The images display well-defined domain structures, which are periodic and commensurate with the holes array.

Magnetic antidot to dot crossover in Co and Py nanopatterned thin films

“…On the one hand, antidots are known to change the magnetization switching mechanisms [12], acting as pinning centers for domain walls (DWs) [13] and enabling novel magnetic domain configurations connected to the array geometry [14][15][16][17][18] * ccastan@unizar.es such as superdomains [11], that are not observed in an unpatterned film. The antidot geometry can also be used to tailor the coercivity H C : many previous studies report an empirical law according to which H C increases linearly with the inverse of the antidot edge-to-edge separation λ = p − d, where d is the antidot diameter and p the array period, for both λ d [19,20] and λ d [21][22][23].…”

Magneto-optic enhancement and magnetic properties in Fe antidot films with hexagonal symmetry

“…At the same time, the holes are pinning sites for domain walls. These two parameters have been shown to influence the coercivities and remanences, 1,2 anisotropies, 3,4 and switching characteristics. 5,6 In parallel, the antidot structures with noble metals have been studied for their optical properties after the pioneering work of Ebbesen et al 7 and the discovery of extraordinary optical transmission of light through these subwavelength structures at certain resonant frequencies or angles of incidence.…”

A micromagnetic study of the reversal mechanism in permalloy antidot arrays

“…[4][5][6][7][8] Magnetotransport and hysteresis properties have been investigated in detail, considering different materials and analyzing the role of lattice configuration, hole shape, and geometrical parameters, such as the hole size and the interhole distance. [9][10][11][12][13][14][15][16][17][18][19][20][21][22][23] Magnetic domain structures arising in antidot arrays have been experimentally observed by means of magnetic force microscopy (MFM), Lorentz microscopy, X-ray photoemission electron microscopy, and magnetooptic Kerr effect measurements. [22][23][24][25][26][27][28][29] The patterning introduces a spatially dependent shape anisotropy that allows the nucleation and propagation of domain walls, influencing in this way the reversal mechanism, the remanent magnetization, and the coercive field.…”

“…[9][10][11][12][13][14][15][16][17][18][19][20][21][22][23] Magnetic domain structures arising in antidot arrays have been experimentally observed by means of magnetic force microscopy (MFM), Lorentz microscopy, X-ray photoemission electron microscopy, and magnetooptic Kerr effect measurements. [22][23][24][25][26][27][28][29] The patterning introduces a spatially dependent shape anisotropy that allows the nucleation and propagation of domain walls, influencing in this way the reversal mechanism, the remanent magnetization, and the coercive field. [9][10][11][12][13][14][15][16] A fourfold anisotropy has been found in square-lattice geometries, while hexagonal and honeycomb configurations exhibit a sixfold symmetry.…”