Large-area patterned magnetic nanostructures by self-assembling of polystyrene nanospheres

Abstract

In this work, dot and anti-dot structures in Co, Ni, Ni 80 Fe 20 , Fe 50 Pd 50 , Fe 73.5 Cu 1 Nb 3 Si 13.5 B 9 and Fe 78 B 13 Si 9 thin films have been produced by means of nanosphere lithography. Two multi-step processes have been followed and will be here described. The first one directly exploits polystyrene nanosheres (PN) as a mask to fabricate arrays of magnetic nanoholes and dots. In the second case, the nanospheres are used to design a polymeric mask of a photoresist subsequently used to pattern a magnetic nanostructure on a film. Advantages and disadvantages of the two lithographical techniques will be here highlighted. In both processes, the dimension and mutual distance of the patterns are dependent on the starting PN diameter (in the interval 500-800 nm). Samples microstructure has been studied by means of SEM and AFM microscopy. Room-temperature hysteresis loops have been measured by an AGFM (Alternating Gradient Field Magnetometer). MFM microscopy has been exploited to study the magnetic domain pattern. All produced systems have been observed to display tunable microstructure and, consequently, various magnetic properties for application.

Bi-Component Nanostructured Arrays of Co Dots Embedded in Ni80Fe20 Antidot Matrix: Synthesis by Self-Assembling of Polystyrene Nanospheres and Magnetic Properties

“…In addition to the BN array, two reference samples have also been prepared, one with an array of Co dots having similar diameter, centre-to-centre distance, and thickness, and one with a Ni 80 Fe 20 antidot (AD) array, with comparable hole geometry and metallic layer thickness. Both have been produced by using the same self-assembling polystyrene nanospheres technique [ 32 ], and will serve as reference samples. Given the characteristics of the fabrication process, the Co dot and Ni 80 Fe 20 antidot arrays of the reference samples shall be considered statistically equivalent to the respective components of the BN sample.…”

“…In this paper, we exploit a self-assembling polystyrene nanospheres lithography process [ 31 , 32 ] to obtain a bi-component nanostructured system composed of Co dots dispersed in a Ni 80 Fe 20 antidot matrix. Through magnetic and magneto-transport investigations, their mutual magnetic interactions will be discussed.…”

Exchange bias study of CoFeB/IrMn antidot and nanodot arrays fabricated by nanosphere lithography

“…Nanosphere lithography (NSL) is a promising low-cost nanofabrication technique for patterning nanostructure arrays. The recent demonstration of magnetic nanodot [24][25][26][27][28][29] and antidot [30][31][32] structures and spin valve nanopillars [33] fabricated by NSL have proved its feasibility in patterning nanostructures for investigating magnetic properties. In this work, NSL is engaged for parallel fabrication of large-area CoFeB/IrMn nanodot and antidot arrays with diameters of less than 100 nm.…”