Investigation of the domain structure transformation under mechanical deformations in permalloy microparticles

Using magnetic force microscopy (MFM) and computer simulation it was shown that the mechanical compression of the permalloy microparticles leads to the increase in the effective anisotropy field and the noticeable decrease in the external magnetic field value necessary for the formation of the uniform magnetization in the compressed particle. The analysis of MFM images of microparticles covering the whole substrate surface made it possible to conclude about the uniform or nonuniform distribution of stresses induced in the particles in the different area of the substrate

Fabrication of magnetic micro- and nanostructures by scanning probe lithography

Planar magnetic structures based on cobalt nanofilms have been obtained by scanning probe lithography. It has been shown that ferromagnetic nanoparticles with different domain structures can be formed by local oxidation of a cobalt film on a graphite substrate with the use of a conductive probe of an atomic force microscope (AFM). Using AFM nanoengraving of polymethylmethacrylate, masks were formed to obtain microcontact pads connected by cobalt nanowires with a width of 250-1400 nm and a thickness of 10-30 nm on the silicon dioxide surface. The topography and magnetization structure of the obtained samples were controlled by atomic and magnetic force microscopy. © Pleiades Publishing, Ltd

Magnetic force microscopy investigation of the magnetization reversal of permalloy particles at high temperatures

© 2014, Pleiades Publishing, Ltd. The magnetization reversal of an array of permalloy particles formed by scanning probe lithography on the silicon dioxide surface has been investigated in the temperature range from room temperature to 800 K. Using scanning magnetic force microscopy and numerical calculations of the magnetic anisotropy field of a particle at different temperatures, it has been shown that an increase in the temperature leads to a decrease in the external magnetic field required to reverse the magnetization direction of the particle. From the obtained results, it has been concluded that the magnetization reversal of the studied particles is accompanied by the formation of an intermediate state with an inhomogeneous magnetization structure

Nickel nanoparticles and nanowires obtained by scanning probe lithography using point indentation technique

A lithographic method of obtaining metal nanowires and nanoparticles on solid substrates is proposed, which employs a polymer mask with windows for the metal deposition formed by indentation in an atomic force microscope. Using this method, Ni nanowires with a minimum width of 60 nm, thicknesses within 6-20 nm, and lengths up to 20 μm and Ni nanoparticles with a preset ordered arrangement have been obtained on a SiO 2 surface. The domain structure in obtained nanoobjects has been studied by the magnetic force microscopy technique. © 2012 Pleiades Publishing, Ltd

Heat-assisted effects in ferromagnetic nanoparticles

The processes of the magnetization reversal by the external magnetic field of the Py particles have been studied by magnetic force microscopy in the temperature range of 300-650 K. The values of the switching field of the particle magnetization and the switching field distribution for the particles array have been determined. The switching field and the field distribution decrease significantly with increasing temperature. © Published under licence by IOP Publishing Ltd

Investigation by MOKE and MFM of the domain structure transformation under mechanical deformations in permalloy microparticles

© Published under licence by IOP Publishing Ltd. In this work, the change in the domain structure of planar permalloy microparticles due to mechanical stress has been studied. For this purpose, an array of particles in a mechanically stressed state was formed on a silicon substrate. In addition, the samples with the array of particles without tension were manufactured. The magnetic structure of the samples was visualized by magnetic force microscopy and hysteresis loops were obtained using the magneto-optical Kerr effect. It was established that the easy magnetization axis collinear to the direction of mechanical stress appears in particles due to mechanical compression. The distribution of magnetization of unstrained particles is mainly determined by the shape anisotropy

Creation of lithographic masks using a scanning probe microscope

© 2015, Pleiades Publishing, Ltd. The experimental results on scanning probe lithography (SPL)—the formation of lithographic masks using scanning probe microscope—are presented. Polymethylmethacrylate (PMMA)-based masks prepared by the SPL method are used to form metal nanoparticles of the specified sizes and shape, as well as the metallic nanowires connecting the contact areas. The analysis of various SPL modes showed that the procedure of point indentation with the switched-on microscope feedback is optimal for the formation of round nanoparticles. When forming the rectangular particles, the procedure of multiple scanning of one region in the contact mode is optimal. The quality of lithographic masks can be substantially increased by the additional use of chemical etching to remove excess PMMA after the mask is formed. The topography and magnetization structure of the formed structures were monitored by atomic force microscopy and magnetic force microscopy

The magnetoelastic effect in permalloy particles

© 2016, Pleiades Publishing, Ltd.Two independent methods—ferromagnetic resonance and magnetic-force microscopy—have been used to study the magnetoelastic effect in permalloy microparticles. The values of effective magnetic-anisotropy fields that are induced by mechanical compression of microparticles have been obtained from the analysis of ferromagnetic-resonance data. These data have been used to model magnetic-force images of stressed and unstressed particles. The images coincide well with experimentally observed ones