Graphene films were grown by the low-pressure chemical vapor deposition with a single injection of acetylene on an iron film catalyst deposited on oxidized silicon substrate. After treatment of the graphene on the iron film with aqueous solution of iron nitrate the structures consisting of quasi-suspended graphene on reaction products of the iron film with iron nitrate were obtained. The electron transport and magnetotransport properties of the films were investigated. The films have a low resistance of 80 Ohm sq−1 and a high sheet carrier density (8 × 1013 cm−2 at room temperature). At temperatures less than 200 K, the dependence of the Hall resistance on the magnetic field is like the abnormal Hall effect. Large positive linear magnetoresistance at a room temperature (60–100%) was observed in the films in a field of 0.6 T, which is attractive for creating magnetoresistive sensors. It was found that the critical magnetic field at which the MR becomes linear is very small (116–650 Oe) and linearly dependent on a temperature. The MR is proportional to the average mobility 〈µ〉. At low temperatures, the magnetoresistance increases with increasing temperature. At higher temperatures the MR decreases with increasing temperature.

Graphene films were grown on an iron film catalyst deposited on oxidized silicon substrate, using the low-pressure chemical vapor deposition. Subsequently the iron film was dissolved with an aqueous solution of iron nitrate. The structures consisting of quasi-suspended graphene on reaction products of an iron film with iron nitrate were obtained. Magnetoresistance properties of the structures were investigated at a room temperature, and the positive magnetoresistance was observed. The maximum magnetoresistance value was 100% in the magnetic field of 0.5T. The dependence of magnetoresistance on the magnetic field was quasi-linear in the range of 0.07–0.5T.

Hybrid structures composed of graphene films and (0001) graphene ribbons perpendicular to the surface of a graphene-like film have been produced through the catalytic decomposition of a carbon-containing gas on an Al-coated SiO2/Si substrate having Ni catalyst islands on its surface. A hybrid structure has been grown by a one-step chemical vapor deposition process, by admitting acetylene into a chamber for a short time. The hybrid structures thus produced have been used to fabricate Hall sensors with a sensitivity of 3000 Ω/T. The synthesized hybrid structures are potential candidates for use in nanoelectronic devices, energy storage systems, etc. The technique proposed for the growth of such films is compatible with technologies that are employed in the electronics industry.

Carbon films were fabricated on oxidized silicon substrates coated by treated bi-layer catalyst film using a chemical vapor deposition (CVD) method with a short-time acetylene inflow. The films consisted of carbon nanotubes and bundles of them, and graphene-like carbon nanostructures. Unusually high magnetic field sensitivity (3000Ω/T) obtained from Hall measurements was observed in the films. The effect of scaling the size of the Hall sensor from carbon films on its magnetic field sensitivity has been investigated. The sensitivity of the Hall sensor with an active area size of 0.13×0.13µm2 was found to be 1140Ω/T, which is much higher than reported in the literature. This carbon material is promising for the fabrication of Hall effect sensors of submicron size.

Пространственное распределение магнитного поля вокруг кончика магнитного кантилевера, покрытого пленкой кобальта толщиной 50 нм, исследовано с помощью FePt-датчика экстраординарного эффекта Холла. Измерена зависимость величины магнитного поля от расстояния между поверхностью датчика и кончиком МСМ-кантилевера: она обратно пропорциональна кубу расстояния, что находится в согласии с теорией. Значение величины магнитного поля, измеренное на кончике МСМ-кантилевера, равно 0.02 Тл.

The spatial distribution of the magnetic field around the tip of a magnetic cantilever coated with a cobalt film 50 nm thick is investigated using an FePt extraordinary Hall effect sensor. The magnetic field’s dependence on the distance between the sensor’s surface and the MFM cantilever is measured and found to be inversely proportional to the cubic distance, as predicted in theory. The magnetic field measured on the MFM cantilever tip is found to be 0.02 T.

The structures of graphene layer-carbon nanotube hybrid films produced via CVD with a single-stage flow of acetylene into a chamber containing a prepared substrate are studied. It is shown that such films have a hybrid double-layer structure consisting of a graphene layer and a dense continuous network of nanotubes. The graphene layer contains continuous extended areas 10–50 μm in size and island areas ∼0.1 μm in size. TEM images lead to the conclusion that the graphene layer and carbon nanotubes are bound by covalent bonds.

Исследована структура гибридных пленок графеновый слой-углеродные нанотрубки, полученных методом СVD с использованием однократного напуска ацетилена в камеру с подготовленной подложкой. Показано, что пленки представляют собой гибридную двухслойную структуру, состоящую из графенового слоя и густой сплошной сетки нанотрубок. Графеновый слой состоит как из сплошных протяженных участков размером 10–50 мкм, так и из островковых участков размером примерно 0.1 мкм. Полученные ПЭМ-изображения позволяют заключить, что в синтезированных гибридных пленках графеновый слой и углеродные нанотрубки связаны между собой ковалентными связями.

Vertically oriented arrays of zinc oxide nanorods with high structural perfection and good optical properties have been obtained by gas-phase synthesis from the elements on the substrates. Homogeneous and heterogeneous e-n transitions have been produced on the basis of these arrays of nanorods. Thermal growth from salt mixtures has been used to synthesize zinc oxide nanorods doped with transition metals (Fe, Mn, Cr). Zinc oxide nanorods doped with iron, manganese, tin, and lithium showed room-temperature ferromagnetic properties. Two-terminal planar structures have been produced from the nanorods doped with chrome. These structures are sensitive to ultraviolet radiation and insensitive to visible light. The field-effect transistor made from the zinc oxide nanorod doped with chrome has electron conductivity and works in the enhancement mode.

Extraordinary Hall effect probes with 160 nm × 160 nm working area were fabricated using photo- and electron-beam lithographic procedures with the aim of direct measurements of MFM cantilever tip magnetic properties. The magnetic field sensitivity of the probes was 35 Ω T−1. Magnetic induction of the MFM cantilever tips coated by Co and SmCo films was measured with the probes. It was shown that the resolution of the probes was of the order of 10 nm.

Исследован экстраординарный эффект Холла (ЭЭХ) для ансамбля наночастиц Co, встроенного в матрицы W и Au. Показано, что величина сигнала ЭЭХ зависит от средневзвешенных толщин как наночастиц Co, так и обволакивающих их матриц. Максимальное значение ЭЭХ получено для средневзвешенных толщин наночастиц Co 0.3–0.6 нм. Величина сигнала ЭЭХ увеличивается также при уменьшении толщины пленки матриц вплоть до нарушения электрической сплошности получаемых структур. В системе Co–W получены структуры с чувствительностью S = U/I H = 32 /T, что открывает возможность создания ферромагнитных датчиков для локальной магнитометрии, работающих при комнатной температуре.

We present a new technique for CVD synthesis of carbon nanotubes without any gas flow and using a very low pressure of acetylene (down to 0.5 mbar). The good quality of obtained nanotubes is confirmed by TEM observation and electron diffraction patterns, Raman spectroscopy and electron transport measurements.

An experimental investigation is presented into the extraordinary Hall effect (EHE) in planar ensembles of Co nanoparticles embedded in a W or Au matrix. The EHE signal strength is shown to depend on the mean thicknesses of both the nanoparticles and the matrix. Its maximum is observed for mean Co thicknesses of 0.3–0.6 nm. The EHE signal is found to grow with decreasing matrix thickness until the structure loses its electrical continuity. A sensitivity as high as S = 32 Θ/T (S = ΔU/IΔH) is achieved with a Co-W film. This result opens up possibilities for building room-temperature ferromagnetic sensors for local magnetometry.

The extraordinary Hall effect was investigated for planar arrays Fe nanoparticles embedded in an ultrathin Pt matrix. It was found that the slope of Hall resistance (RH) reversed sign at ±0.15T for Fe particles of mean thickness 0.3nm. The dependence is presumably due to the effect of two spin-orbital induced mechanisms of carriers scattering, skew scattering, and side jump, with the skew component of positive sign and the side jump component of negative sign. For Fe samples, 0.6nm thick RH increases monotonically with the magnetic field value. At low temperatures, the superparamagnetism of the samples disappeared.

An experimental study is presented on the extraordinary and the ordinary Hall effect in ultrathin Fe-Pt films down to 1.5 nm thick deposited by laser ablation in a high vacuum. The variation of the Hall coefficients with film thickness is investigated. It is shown that the extraordinary Hall coefficient varies as film resistivity and grows with decreasing film thickness. The extraordinary and the ordinary Hall coefficient are found to depend on the substrate material.

Fe – Pt alloy thin and ultra thin films were deposited by the pulse laser evaporation method. Micronano Hall devices were fabricated from ultra thin films by an Ar plasma etching process using electron beam lithography procedures. The extraordinary Hall effect (EHE) in Fe – Pt alloy thin and ultra thin films and micronano Hall devices was investigated. The film thickness reduction is found to cause an increase in Hall voltage, which means an enhancement of field sensitivity of the Hall sensor. Maximum sensitivity S=260 Ω/ T was measured in ultra thin film with thickness d=20 Å.

The interaction of manganese and some 4 f -metals (M) with silver iodide is studied. The samples are obtained by sputtering M onto the surface of polycrystalline AgI films (∼ 0.2 μm, ∼ 300 K) in a vacuum. Optical absorption in the samples is interpreted as the insertion of M ions into AgI with the formation of dopants AgI:M. A new phase with an optical bandgap of ∼ 3.7 eV emerges in the samples with elevated concentrations of La, Ce, Pr, Nd, Sm, or Dy ( n M / n Ag ∼ 0.1). X-ray diffraction patterns for such samples with Sm correspond to structures with large interfacial distances, for example, 0.99, 0.87, 0.76, and 0.67 nm. In air, AgI forms in the samples with a new phase; this process is hindered by the sputtered protective coatings. According to optical absorption data, X-ray diffraction, and local microanalysis the Mn insertion into AgI is followed by the formation of a new phase (2Ag:Mn:4I), which may belong with solid electrolytes Ag 2 MI 4 , where nonmagnetic M are known (Zn, Cd, Sn, Hg, Pb).

The work was made in a development of the previous ideas [3]. Interaction of some 3d- and 4f-metals (M) with AgI and CuI were studied. The samples were created at ~300 K by a vacuum deposition of M onto the AgI or CuI polycrystalline films ( thickness ~0.08 -0.2 µ). Optical absorption of samples was interpreted as an insertion at the first stage of M-ions into AgI (wurtzite, zincblende or their mixture) with the formation of AgI:M dopants and then (at an increase of concentration of La, Ce, Pr, Nd, Sm or Dy up to n/n ~0.1) as the precipitation of new compounds with band gap ≈3.7 eV. Debye’s pictures of the samarium silver iodide compound correspond to the structure with the large interlayer distances, for example, 10.07 (9.78), 8.86 (8,68), 7.56 (7.67) И 6.72 (6.68) A. At a storage of such samples in air, the precipitation of AgI was observed. The deposition of the defense layers onto samples puts an obstacle for the above mentioned process. According the optical absorption and x-ray data, after a stage of insertion of Mn into AgI takes place next stage (the stage of precipitation of new compound). This compound coexists with AgI and the phase of metal silver. At the increase of Mn content in the samples, the portion of AgI decreased. The bands of optical absorption with maxima 3.35 ± 0.02 eV and 3.62 ± 0.02 eV (300 K) were discovered for this compound. The local microanalysis had shown that manganese silver iodide has 2Ag:Mn:4I content. Therefore it may belong to the M′M″I solid electrolyte-superionic conductor family where are known the non-magnetics M′- Cu, Ag and M″ - Zn, Cd, Sn, Hg and Pb. At the analogous experiments with an insertion of Mn into CuI, the bands of optical absorption with maxima 3.42 ± 0.02 eV and 3.72 ± 0.02 eV (300 K) were discovered in the spectra. Thus the manganese copper iodide (CuMI) must also belong to the M’M I solid electrolyte family. The role of the first ionization energy of M in the generating of the initial elementary acts for the process of insertion of M into AgI and CuI had been clarified with using of AgI-Fe, CuI-Fe, AgI-Ni and CuI-Ni film systems. The prediction of insertion of actinoid and 4d-elements into AgI and CuI is made.