Here we describe a method of forming large arrays (up to 10(9) pieces) of free magnetic Ni-nanodisks 50 nm thick coated on both sides with layers of 5 nm thick Au. The antitumor effect of the magnetic nickel gold-coated nanodisks and DNA aptamer conjugates was evaluated in vivo and in vitro. Under the influence of rotating magnetic field, the studied nanodisks can cause the death of Ehrlich ascites carcinoma cells.
The lift of the degeneracy of the resonance frequency of motion of the core of a magnetic vortex in a square array of nanodots has been experimentally detected. The appearance of a frequency multiplet has been the oretically explained. It has been shown that a reason for the lift of degeneracy can be the magnetostatic inter action between nanodots.
Development of the interpretation of the phenomenon of the lift of the magnetic resonance frequencies degeneracy caused by the magnetostatic interaction in assemblies of nanodisks has been done. The difference of the resonance behavior of magnetic vortexes in a round and rectangular nanodots has been studied experimentally and explained.
The present day interest in micron and submicron magnetic objects is stimulated, in particular, by their possible applications in computer engineering [1][2][3][4] and biomedicine [5,6]. In the majority of publica tions, of concern is the problem of film disk shaped spots. For reasonably small sizes of a disk, the mag netic vortex is formed with circular magnetization in the spot plane on the periphery and with the magneti zation outcrop from the plane in the center (the vortex core). The magnetic interaction of two or more vorti ces is many times less intense than the interaction of uniformly magnetized magnetic cells of the same shape and volume, which makes it possible to decrease the sizes of spots with the vortex structure and, thus, considerably increase the information density in the medium. In dependence on the direction of core mag netization (conditionally upwards or downwards), one distinguishes the positive and negative vortex polariza tions and the direction of the magnetic flux closure of the vortex flat part determines its chirality (right or left). The store of information (0 or 1) in a cell with the vortex magnetic structure is possible in two ways: according to the sign of polarization and according to the type of chirality (right or left). The purpose of this investigation is to study the effect of sizes and shapes of a spot on its magnetic structure and to clarify the prac tical prospects of spots of different shape-square and triangular in addition to circular.
EXPERIMENTAL EQUIPMENTAND RESULTS Permalloy film spots of 30-60 nm thick with trans verse sizes from 20 to 1 µm were the object of investi gation. The samples were made by photolithography from a continuous film obtained by the method of vac uum condensation of vapors of an initial material (permalloy Ni 80 Fe 20 ) on a glass substrate. For the Lorentz microscopy, the metal vapors were deposited on a substrate (formvar) transparent to the electron beam through a grid with square cells. The magnetic structures were visualized with the help of a VEECO multimode III magnetic force microscope, an UEMV 100A electron microscope, and an MBI 6 optical microscope (using a FER 01 diluted ferrofluid as the magnetic suspension).In Fig. 1, we show the patterns of magnetic struc tures characteristic for permalloy spots of circular, square, and triangular shape. In the case of circular spots of 5 µm in diameter and smaller in the thickness range of 30-50 nm, a steady equilibrium structure of the classical magnetic vortex with a central core arises. For square spots, it is a structure with a closed mag netic flux (quasi vortex) composed of four domains with the magnetization oriented along the adjoining side of the square that is equilibrium; the domains are separated with an approximately 90 degree Néel boundaries and with the Bloch point (quasi core) in the structure center. It is characteristic for all investi gated sizes of the spot and film thicknesses. In the case of triangular spots, the quasi vortex with a quasi core is also formed, but the sp...
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.