Rustam Khaibullin | Kazan Federal University (original) (raw)

Papers by Rustam Khaibullin

Physics of the Solid State

The natural beryl crystals have been irradiated by 40 keV iron ions with fluence of 1.5xl017 ion/... more The natural beryl crystals have been irradiated by 40 keV iron ions with fluence of 1.5xl017 ion/cm2 on an ion beam accelerator. For an annealing of radiation defects and a redistribution of implanted iron ions, the thermal treatment of irradiated beryls has been performed in oxygen during 30 min. at 600 °C. Crystal-chemical peculiarities of irradiated beryls were then investigated by optical absorption and Mössbauer spectroscopy. Iron irradiation and following a thermal annealing of non-colored beryl have led to alteration of color of crystals into orangeyellow. It was established that the iron ions implanted in beryl's structure are localized in octahedral and tetrahedral sites, where they substitute aluminum and beryllium ions by isomorphic way.

Physical Review Materials

We report investigation of ferromagnetic resonance phenomenon in ferromagnetic thin films with es... more We report investigation of ferromagnetic resonance phenomenon in ferromagnetic thin films with essentially non-uniform composition. Epitaxial Pd-Fe thin film with linear distribution of Fe content across the thickness is used as the model material. Anomalous perpendicular standing spin waves are observed and quantified using the collective dynamic equation. Numerical analysis yields the exchange stiffness constant for diluted Pd-Fe alloy D = 2A/µ0Ms = 15 T•nm 2 and the ratio of the effective magnetization to the saturation magnetization M ef f /Ms = 1.16. It is demonstrated that, overall, engineering of thin films with non-uniform composition across the thickness can be used for high-frequency or low-field magnonic operations using exchange spin waves.

Crystals

In this work, we report on the endotaxial growth of α-Fe nanoparticles in the near-surface layer ... more In this work, we report on the endotaxial growth of α-Fe nanoparticles in the near-surface layer under high-fluence iron ion implantation of the single-crystal magnesium oxide substrate. Comprehensive Mössbauer effect and magnetometry studies show that the implanted sample reveals a pronounced ferromagnetic response even at room temperature, and the α-Fe nanoparticles serve as its main source. The broad band at ~1000 Oe in the X-band magnetic resonance spectra originates from the α-Fe fraction. It manifests the properties of the easy-plane system with the four-fold in-plane anisotropy. The last indicates that the α-Fe nanoparticles are coherently incorporated into the host MgO matrix.

Materials Letters, 2021

We report on the formation of the dilute Pd1-xFex compositions with tunable magnetic properties u... more We report on the formation of the dilute Pd1-xFex compositions with tunable magnetic properties under an ion-beam implantation of epitaxial Pd thin films. Binary Pd1-xFex alloys with a mean iron content x of 0.025, 0.035 or 0.075 were obtained by the implantation of 40 keV Fe + ions into the palladium films on MgO (001) substrate to the doses of 0.5•10 16 , 1.0•10 16 and 3.0•10 16 ions/cm 2 , respectively. Structural and magnetic studies have shown that iron atoms occupy regular fcc-lattice Pd-sites without the formation of any secondary crystallographic phase. All the iron implanted Pd films reveal ferromagnetism at low temperatures (below 200 K) with both the Curie temperature and saturation magnetization determined by the implanted iron dose. In contrast to the magnetic properties of the molecular beam epitaxy grown Pd1-xFex alloy films with the similar iron contents, the Fe-implanted Pd films possess weaker in-plane magnetocrystalline anisotropy, and, accordingly, a lower coercivity. The observed multiple ferromagnetic resonances in the implanted Pd1-xFex films indicate a formation of a magnetically inhomogeneous state due to spinodal decomposition into regions, presumably layers, with identical crystal symmetry but different iron contents. The multiphase magnetic structure is robust with respect to the vacuum annealing at 770 K, though develops towards well-defined local Pd-Fe compositions.

Crystallography Reports, 2018

Implantation of high-energy helium ions into crystals of natural colorless diamonds colors them b... more Implantation of high-energy helium ions into crystals of natural colorless diamonds colors them bright yellow, brown, or black, depending on the implantation dose. The nature of the induced fantasy color and crystal-chemical features of the implanted diamonds have been investigated by IR spectroscopy and Raman spectroscopy. It is established that the radiation effect of helium ions on the diamond crystal structure results in the transformation of nitrogen-vacancy centers in its bulk with the formation of new A-type color centers, as well as the formation of carbon nanoclusters with the sp 2 hybridization of bonds (which is typical of graphite) in black diamonds.

Russian Microelectronics, 2018

⎯Iron and nickel nanowires are grown by the matrix synthesis technique in the pores of the track ... more ⎯Iron and nickel nanowires are grown by the matrix synthesis technique in the pores of the track membrane fabricated based on polyethylene terephthalate (PET). Scanning electron microscopy (SEM) and atomic force microscopy (AFM) are used to image the pores on the surface of the specimens and determine the 3d metal nanowires in a polymer bulk. The magnetization curves of the arrays of the nanowires are obtained. Magnetic properties of the nanowires are studied by the magnetic force microscopy (MFM) methods. The influence of the interposition and magnetostatic interaction of the nanowires of the magnetic metals in the polymer membrane, as well as the magnitudes and orientation of the applied external magnetic field, on the obtained MFM images is shown. The simulation results of the MFM images are in good agreement with the experimental data.

Journal of Physics: Conference Series, 2017

We present the results of magnetic and Mössbauer effect studies of zinc oxide thin film obtained ... more We present the results of magnetic and Mössbauer effect studies of zinc oxide thin film obtained by RF magnetron sputtering and implanted with 40 keV iron ions to a fluence of 1.5•10 17 ion/cm 2. As-implanted and post-annealed sample shows ferromagnetic properties at room temperature and consists of paramagnetic and ferromagnetic phases according to Mössbauer spectroscopy.

Journal of Surface Investigation: X-ray, Synchrotron and Neutron Techniques, 2017

Modification of the surface layers of polyimide films under γ-radiation and implantation with 30-... more Modification of the surface layers of polyimide films under γ-radiation and implantation with 30-100 keV Ni, Mn, Ag, Co, Fe and B ions in the dose range of 10 15-1.5 × 10 17 cm-2 are investigated by reflection spectra measurements. Ion implantation is shown to lead to the modification of reflection from the rear (unimplanted) polymer side. Depending on the kind of ion and implantation mode a strong increase in the integrated reflection coefficient in the polymer opacity range is observed, as well as growth of the reflection intensity of optical bands λ 1 = 254 and λ 2 = 311 nm and their shifts to the short-wavelength region. The change in the reflection coefficient far beyond the implanted region is caused by the radiation-induced transformation of the polymer supermolecular structure near the surface and the relaxation of mechanical stress formed during film production.

Nanostructured Magnetic Materials and their Applications, 2004

Different polymers (viscous-flow epoxies, viscoelastic silicone resins and solid state polyimides... more Different polymers (viscous-flow epoxies, viscoelastic silicone resins and solid state polyimides) were implanted with 40 keV Fe+ or Co+ ions to the doses of 0.1÷2.0×1017 ions/cm2. The influence of the dose and viscosity of polymer target on the process of nucleation and growth of metal nanoparticles in the implanted polymers as well as on the magnetic properties of ion-synthesized composites were investigated by electron microscopy and magnetic resonance. The implantation of the polymers with 40 keV ions causes a surface carbonization of polymer substrate and at the doses more than 0.25×1017 ions/cm2 results in the formation of metal (iron or cobalt) nanophase in thin subsurface layer. Mean sizes, crystalline structure, shape and space packing of the ion-synthesized nanoparticles strongly depend on the dose, kind of implanted ions and the polymer viscosity during implantation. The ion synthesis of the isolated cubic or spherical particles with the mean sizes in the range of 2÷200 nm, as well the formation of many-particles clusters, fractal-type agglomerates and single microscaled plates are observed in the implanted polymers under study. Ion-synthesized iron or cobalt nanoparticles reveal the magnetic resonance response, and at high doses their resonance signals demonstrate the typical features of ferromagnetic resonance in granular magnetic films. The values of magnetization and coercivity of the granular composite films were obtained from the analysis of FMR data. The non-linear dependencies of the composite magnetization on ion dose and on the viscosity of polymer target are presented and discussed in the frame of the magnetic percolation transition in the many-particles system.

Journal of Magnetism and Magnetic Materials, 2015

Abstract The magnetic properties of Ni-implanted ITO thin films have been investigated by ferroma... more Abstract The magnetic properties of Ni-implanted ITO thin films have been investigated by ferromagnetic resonance (FMR) technique and vibrating sample magnetometry (VSM) techniques. Commercially available ITO thin films on fused silica substrates have been implanted with different fluences of Ni+ ions with energy of 40 keV and ion current density of 8 µA/cm2 at room temperature. The samples with three doses of 0.5×1017, 1.0×1017 and 1.5×1017 ions/cm2 have been studied. Room temperature ferromagnetism has been observed in the nickel-implanted ITO samples with fluences of 1.0×1017 and 1.5×1017 ions/cm2. The magnetic properties of the samples have been explained by the formation of Ni-nanoparticles in the implanted surface layer of the ITO films. Although the formation of a diluted magnetic oxide phase cannot be ruled out entirely, the analysis of our FMR and VSM data reveals that the metallic Ni nanoparticles, formed during high-dose implantation process, have major contribution to the magnetic properties of the Ni-implanted ITO thin films. The sizes of the Ni-nanoparticles have been calculated from the blocking temperatures obtained by the VSM measurements. The filling factor of the Ni ferromagnetic phase in the granular magnetic layer has also been estimated by the effective magnetization approach applied to the FMR results.

Technical Physics, 2002

Ar + and Ar 2+ ions with energies of 40 and 80 keV are implanted into thin polyimide films. The i... more Ar + and Ar 2+ ions with energies of 40 and 80 keV are implanted into thin polyimide films. The implant doses and the ion current densities are varied in a wide range between 2.5 × 10 14 and 1.5 × 10 17 cm-2 and between 1 and 16 µ A/cm 2 , respectively. The effect of the implantation parameters on the electrical, paramagnetic, and optical properties of the ion-modified near-surface polymer layer is studied. It is shown that the radiation-stimulated thermolysis of polyimide and its chemical constitution are responsible for a monotonic growth of the electrical conductivity of the layer with increasing ion current at a given implant dose. When the ion current density is fixed, the conductivity grows stepwise with implant dose, whereas the concentration of paramagnetic centers and the optical transmission of the modified layer decrease. The dependences observed are treated within a model of the structural reconfiguration of the polymer carbonized phase formed during the implantation.

Surface and Coatings Technology, 1998

ABSTRACT The polymer molecule mobility as an ion implantation synthesis parameter controlling nuc... more ABSTRACT The polymer molecule mobility as an ion implantation synthesis parameter controlling nucleation and growth processes of the metal nanoparticles in the organic matrix is considered. The size, shape and crystal structure of synthesized nanoparticles are determined by the substrate molecule mobility (viscosity) as shown for the cobalt ion implantation into the viscous epoxy. Under the conditions of the liquid polymer structure homogeneity (viscosity less than 50Pa·s), the implanted atoms condense into spherical nanoparticles with a narrow size distribution. At a polymer viscosity of 50Pa·s and above, the morphology and phase composition of the dispersion metal film are defined by the forming supermolecular structure of cured polymer. It is shown that spatially oriented nanostructures of metal particles and quasi-continuous monocrystal thin films can be produced also by implantation in the viscous polymer.

Journal of Magnetism and Magnetic Materials, 2004

Co + ions of 40 keV were implanted in thin polyimide foils with doses in the range of (0.25-1.50)... more Co + ions of 40 keV were implanted in thin polyimide foils with doses in the range of (0.25-1.50) Â 10 17 ions/cm 2 at ion current densities of 4, 8 and 12 mA/cm 2. The cobalt-implanted polymer foils were annealed at a temperature of 300 C for 2 h in vacuum. Both the as-implanted and post-annealed samples were investigated by the ferromagnetic resonance (FMR) technique supplemented by transmission electron microscopy (TEM). TEM investigations showed that the implantation results in the formation of cobalt granules in the irradiated polymer layer with the thickness of about 70 nm. The mean lateral size of cobalt granules varied within 5-20 nm depending on the dose. The annealing of the implanted samples induced coalescence of the cobalt granules and increase of their lateral sizes. No FMR signals were found for the as-prepared polymer foils implanted by cobalt ions at low current density of 4 mA/cm 2. FMR signals were observed for the as-prepared samples implanted at higher ion current densities of 8 and 12 mA/cm 2 as well as for all annealed samples. The values of the effective magnetisation were extracted from the FMR spectra measured at different sample orientations in the applied magnetic field. Dose dependencies of the FMR absorption intensity and effective magnetisation were obtained for the annealed films. The magnetic properties of the synthesised cobalt-polymer composite materials and their modification due to the annealing treatment are discussed.

Microelectronic Engineering, 2003

1 1 17 2 Polyimide foils were implanted with 40 keV Fe and Co to doses of 0.25-1.5310 ions / cm. ... more 1 1 17 2 Polyimide foils were implanted with 40 keV Fe and Co to doses of 0.25-1.5310 ions / cm. Electron microscopy studies showed the formation of iron and cobalt nanoparticles in the implanted polymer layer with a thickness of about 70 nm. The size and shape of the ion-synthesized metal nanoparticles depend on the implantation parameters and subsequent thermal annealing. A ferromagnetic resonance (FMR) response was found in the iron-implanted samples as well as in the annealed cobalt and iron samples. The effective magnetization values of the metal / polymer composite layers were extracted from the FMR spectra and plotted as a function of implantation dose. The magnetic properties of the iron and cobalt nanoparticles in polyimide are compared and discussed.

Journal of Applied Spectroscopy, 2020

Optical transmission and reflection spectra of monocrystalline zinc oxide (ZnO) plates implanted ... more Optical transmission and reflection spectra of monocrystalline zinc oxide (ZnO) plates implanted with 40 keV Co + ions to high doses of (0.5–1.5)·10 17 cm –2 are presented. With increasing dose, the transmission value decreases and the optical transmission edge shifts towards the long-wavelength region in transmission spectra. Also, in the transmission spectra, three absorption bands are observed in the range of 550–680 nm. The bands and their positions are typical of optically active Co 2+ ions in the zinc cation substitution positions in the ZnO matrix. The reflection coefficient of the implanted side of the ZnO plate increases monotonically with increasing dose values. In both the initial and implanted ZnO plates, when reflection spectra are recorded from the reverse (nonirradiated) side, a characteristic structure at l = 375 nm is observed due to exciton reflection. Modeling of light transmission and reflection in cobalt-implanted ZnO samples was carried out within the framework of a three-layer model, in which the first surface layer contains cobalt nanoinclusions, the second, deeper layer is a solid solution of cobalt ion substitution in the ZnO matrix, the third layer is the unirradiated part of the ZnO plate. Modeling was used to determine effective refractive indices of two ZnO layers containing implanted cobalt admixture in different phase states.

Applied Magnetic Resonance, 2017

Single-crystal (100) and (001) TiO 2 rutile substrates have been implanted with 40 keV Fe ? at ro... more Single-crystal (100) and (001) TiO 2 rutile substrates have been implanted with 40 keV Fe ? at room temperature with high doses in the range of (0.5-1.5) 9 10 17 ions/cm 2. A ferromagnetic resonance (FMR) signal has been observed for all samples with the intensity and the out-of-plane anisotropy increasing with the implantation dose. The FMR signal has been related to the formation of a percolated metal layer consisting of close-packed iron nanoparticles in the implanted region of TiO 2 substrate. Electron spin resonance (ESR) signal of paramagnetic Fe 3? ions substituting Ti 4? positions in the TiO 2 rutile structure has been also observed. The dependences of FMR resonance fields on the DC magnetic field orientation reveal a strong in-plane anisotropy for both (100) and (001) substrate planes. An origin of the in-plane anisotropy of FMR signal is attributed to the textured growth of the iron nanoparticles. As result of the nanoparticle growth aligned with respect to the structure of the rutile host, the in-plane magnetic anisotropy of the samples reflects the symmetry of the crystal structure of the TiO 2 substrates. Crystallographic directions of the preferential growth of iron nanoparticles have been determined by computer modeling of anisotropic ESR signal of substitutional Fe 3? ions.

Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 2007

Fe + ions (40 keV) were implanted into polyethyleneterephthalate (PET) films with fluences of (0.... more Fe + ions (40 keV) were implanted into polyethyleneterephthalate (PET) films with fluences of (0.25-1.5) • 10 17 cm À2. Magnetic properties of the synthesised Fe:PET composites were studied using superconducting quantum interference device (SQUID) technique in temperature range of 2-300 K. For range of fluences (0.5-0.75) • 10 17 cm À2 the samples reveal superparamagnetic behaviour at room temperature. At fluences above 0.75 • 10 17 cm À2 the strong increase of magnetisation and transition to ferromagnetic properties are registered. Analysis of the magnetic hysteresis loops suggests an easy plane magnetic anisotropy similar to that found for thin magnetic films. Zero-field-cooled (ZFC) and field-cooled (FC) temperature measurements of magnetisation are found to be in agreement with earlier observed formation of Fe nanoparticles (NPs) in the implanted layers. The growth and agglomeration of the NPs forming the quasi-continuous labyrinth-like structure in the polymer film at the highest implantation fluence of 1.5 • 10 17 cm À2 is an origin for the transition to the ferromagnetic properties.

Materials Research Bulletin, 2011