Reversal mechanisms in perpendicularly magnetized nanostructures

Abstract

We demonstrate that magnetic reversal in perpendicularly magnetized nanostructures is highly dependent on the nature and condition of the edges. To understand the impact of edge damage, we compare nanostructures created by ion milling to those prepared on prepatterned substrates. The size-and temperature-dependent reversal properties of 25 nm-1 m diameter nanodots show that reversal in prepatterned nanostructures is controlled by nucleation within the interior, whereas ion milling results in an edge nucleation process with an unpredicted temperature dependence of the reversal field.

Enhanced Hall effect in Co/Pd multilayered nanodomes with perpendicular anisotropy

“…The multilayers arrangement consists in Pd(1nm)/[Co(0.4nm)/Pd(1nm)] x10 , covered by an additional 2 nm of Pd to avoid oxidation. The base pressure in the chamber was 8×10 7 Torr, and the Ar pressure during deposition was kept at 3 mTorr using 20 sccm Ar flow. Reference samples have been also deposited at the same time on glass substrates, and Hall cross masks of 1 mm width have been used during sputtering for posterior Hall effect measurements in all samples.…”

“…4,5 The research and potential applications of nanopatterned PMA films is still more exciting, since the patterns can have length scales similar to the domain-wall widths and can be tailored to limit the domain-wall propagation, [6][7][8] and to observe new magnetic phenomena as magnetic skyrmions. 9 Methods for fabrication of nanopaterned PMA films include lithography or self-assembling block copolymers.…”

Development of vortex state in circular magnetic nanodots: Theory and experiment

“…1͒-before returning this field to zero, leaving only the 34 Oe out-of-plane field. 24 These quantitative measurements yield the out-of-plane magnetization of the dot in the vortex state, i.e., the magnetization of the vortex core, 140Ϯ 50 emu/ cm 3 . An equivalent Fe cylinder with the same magnetization would have a diameter of 19Ϯ 4 nm.…”

“…One of the most studied types of such structures are nanoscaled disks denoted as "nanodots" which have been reproducibly fabricated by variety of techniques. [3][4][5][6] In these magnetic dots, many different magnetic configurations appear and at a particular length scale, a magnetic vortex may become the ground state. 1,7,8 This is caused by an intricate balance between the different relevant energy contributions: anisotropy ͑surface, boundary, etc.͒, Zeeman, and exchange.…”

Energy barriers in patterned media

“…Magnetic calculations made by Uesaka et al (1995) on magnetic hexagonal particles with perpendicular magnetic anisotropy show that a region of low anisotropy at a corner of the particle results in an asymmetric angular dependence of the switching field as well. In our case etching damage or redeposition of a magnetic layer on the edge of the island during etching could be the origin of anisotropy reduction (Shaw et al, 2008). It should be noted however that the demagnetisation field is smaller at the edge of a perfect island, so in principle nucleation of a reversed domain should start in the centre of the island.…”