No abstract

In recent years, much research effort has been devoted to obtaining arrays of organized nanostruc tures, which offer promising applications in semicon ductor technology, magnetooptics, sensor technology, and data storage devices [1][2][3]. Special attention has been given to arrays of magnetic nanowires, which have good prospects as magnetic recording media. However, fabrication of structures with desired char acteristics on a submicron scale requires using expen sive and laborious methods of electron beam and focused laser beam lithography. An alternative approach to obtaining magnetic nanowires is based on non catalytic synthesis of nanocolumnar film struc tures [4]. The formation of nitride-carbon nanotubu lar structures, which grow perpendicular to a substrate in the course of magnetron sputtering of a target, takes place provided that nitrogen is present in the growth atmosphere. This notion concerning the role of nitro gen is confirmed, in particular, by the growth of fullerene like films of carbon nitride [5].The process of magnetron sputtering of magnetic metals with the formation of nanocolumnar film structures is almost unstudied. The present work was aimed at obtaining nanocolumnar nickel films by magnetron sputtering in a nitrogen containing atmo sphere and studying the magnetic properties of these films with allowance for the presence of nitrogen dis solved in the deposited metal.The samples of nanocolumnar nickel films on glass substrates were prepared by the magnetron sputtering of a nickel target (special purity grade Ni) in argon atmosphere containing 2 vol % N 2 . The working pres sure of the gas mixture was ~25 Pa and the substrate temperature was ~530 K. A series of films were pre pared by sputter deposition at a constant rate (~10 nm/min) for various times (3-60 min), so that the corresponding film thicknesses varied from ~30 tõ 600 nm. The surface morphology of films was studied and their thicknesses (in the transverse cleavage) were determined by field emission scanning electron microscopy (SEM) on a JSM 6490 LV (JEOL) instru ment. The relative content of nitrogen in the samples was determined by energy dispersive X ray (EDX) spectroscopy using an INCA Penta FETx3 (Oxford Instruments) attachment. The structure of samples was studied by X ray diffraction (XRD) on a DRON 3 instrument using CoK α radiation.The saturation magnetization and its temperature dependence in nickel films were studied using an induction-frequency setup [6], in which a change in the resonance frequency ΔF ∝ ΔM = f(H) was mea sured for an oscillatory circuit with a sample placed in the induction coil. Using this method, it is possible to directly measure the saturation magnetization of a fer romagnetic film. The principle of measurement is based upon the fact that the sample is essentially two dimensional. When this sample is magnetized perpen dicular to its plane, a "demagnetizing" field is equal to the saturation magnetization 4πM S (in the SGSM sys tem). If the applied magnetic field H ext is varied, the setup measur...

Nanostructured hybrid Ni-CNx films were grown by magnetron sputtering of a composite graphite-nickel target. Atomic force microscopy showed the clustered nature of the films deposition on the substrate surface: a relatively high pressure in the low-temperature magnetron plasma made it possible to form the Ni@CNx nanoclusters type "core-shell", where metallic nickel is the core and carbon nitride is the shell. When studying the role of carbon in the formation of the structure and properties of Ni@CNx nanoclusters, it was established that the saturation magnetization 4πMs of nanoclusters drops sharply with a carbon content above 30 at.%. The reason is the formation of an increasingly saturated solid solution of carbon in nickel. At a carbon concentrations above 38 at.%, amorphous Ni-CNx nanoclusters are formed in the magnetron plasma, which are deposited on the substrate. An increase in the substrate temperature leads to the crystallization of Ni atoms, and the C and N atoms are forced out onto the surface of the nickel core, forming an array of Ni@CNx elements.

Carbon‐nitride nanocolumns were produced without catalyst metal by dc magnetron sputtering of a graphite target in pure N2 gas at pressure of 26.0 Pa on a quartz glass substrate kept at ∼200 °C. The nitrogen/carbon ratio in nanocolumns equals 0.18. Scanning electron microscopy shows that films represent dense nanostructure with columns ∼70–80 nm in diameter. The main fraction of the nitrogen is sp2‐coordinated by carbon and enters into the graphene layers as substitutional atoms; the other fraction of the nitrogen facilitates a cross‐linking between the graphene layers through sp3‐coordinated carbon.