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.
Magnetic nanoparticles embedded into semiconductors have current perspectives for use in semiconducting spintronics. In this work, 40 keV Fe+ ions were implanted in high fluences of (0.5 ÷ 1.5) × ...1017 ion/cm2 into an oxide semiconductor and single-crystalline TiO2 plates of rutile structure with (100) or (001) face orientations. Microstructure, elemental-phase composition, and magnetic properties of the Fe-ion-implanted TiO2 were studied by scanning and transmission electron microscopies (SEM and TEM), X-ray photoelectron (XPS) and Rutherford backscattering (RBS) spectroscopies, as well as vibrating-sample magnetometry (VSM). The high-fluence ion implantation results in the formation of magnetic nanoparticles of metallic iron beneath the irradiated surface of rutile. The induced ferromagnetism and observed two- or four-fold magnetic anisotropy are associated with the endotaxial growth of Fe nanoparticles oriented along the crystallographic axes of TiO2.
In this work, we have studied the microstructure and unusual ferromagnetic behavior in epitaxial tin dioxide (SnO2) films implanted with 40 keV Co+ ions to a high fluence of 1.0 × 1017 ions/cm2 at ...room or elevated substrate temperatures. The aim was to comprehensively understand the interplay between cobalt implant distribution, crystal defects (such as oxygen vacancies), and magnetic properties of Co-implanted SnO2 films, which have potential applications in spintronics. We have utilized scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), vibrating sample magnetometry (VSM), differential thermomagnetic analysis (DTMA), and ferromagnetic resonance (FMR) to investigate Co-implanted epitaxial SnO2 films. The comprehensive experimental investigation shows that the Co ion implantation with high cobalt concentration induces significant changes in the microstructure of SnO2 films, leading to the appearance of ferromagnetism with the Curie temperature significantly above the room temperature. We also established a strong influence of implantation temperature and subsequent high-temperature annealing in air or under vacuum on the magnetic properties of Co-implanted SnO2 films. In addition, we report a strong chemical effect of ethanol on the FMR spectra. The obtained results are discussed within the model of two magnetic layers, with different concentrations and valence states of the implanted cobalt, and with a high content of oxygen vacancies.
The results of a study of heavy implantation of a LiNbO3 crystal with iron ions are reported for the first time. The X-cut LiNbO3 substrate was implanted with 40-keV Fe+ ions to the fluence of ...1.5·1017 ions/cm2. The sample reveals pronounced ferromagnetic properties at room temperature. However, the ferromagnetic response observed in the iron-implanted LiNbO3 differs from the magnetic behavior of other oxides implanted with iron ions under the same conditions. This difference occurs from the unusual magnetic phase composition of the implanted surface layer of the LiNbO3 in which the iron implant precipitates in the form of the nanoscale alloy of metallic iron with niobium. Based on Mössbauer spectroscopy data, we estimated the Nb content in the ion-synthesized nanosized alloy as ~12 at.%, which is much higher than the solid solubility limit of Nb in bulk Fe.
The results of a study of heavy implantation of a LiNbOsub.3 crystal with iron ions are reported for the first time. The X-cut LiNbOsub.3 substrate was implanted with 40-keV Fesup.+ ions to the ...fluence of 1.5·10sup.17 ions/cmsup.2 . The sample reveals pronounced ferromagnetic properties at room temperature. However, the ferromagnetic response observed in the iron-implanted LiNbOsub.3 differs from the magnetic behavior of other oxides implanted with iron ions under the same conditions. This difference occurs from the unusual magnetic phase composition of the implanted surface layer of the LiNbOsub.3 in which the iron implant precipitates in the form of the nanoscale alloy of metallic iron with niobium. Based on Mössbauer spectroscopy data, we estimated the Nb content in the ion-synthesized nanosized alloy as ~12 at.%, which is much higher than the solid solubility limit of Nb in bulk Fe.
In this work, we have studied the microstructure and unusual ferromagnetic behavior in epitaxial tin dioxide (SnOsub.2) films implanted with 40 keV Cosup.+ ions to a high fluence of 1.0 × 10sup.17 ...ions/cmsup.2 at room or elevated substrate temperatures. The aim was to comprehensively understand the interplay between cobalt implant distribution, crystal defects (such as oxygen vacancies), and magnetic properties of Co-implanted SnOsub.2 films, which have potential applications in spintronics. We have utilized scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), vibrating sample magnetometry (VSM), differential thermomagnetic analysis (DTMA), and ferromagnetic resonance (FMR) to investigate Co-implanted epitaxial SnOsub.2 films. The comprehensive experimental investigation shows that the Co ion implantation with high cobalt concentration induces significant changes in the microstructure of SnOsub.2 films, leading to the appearance of ferromagnetism with the Curie temperature significantly above the room temperature. We also established a strong influence of implantation temperature and subsequent high-temperature annealing in air or under vacuum on the magnetic properties of Co-implanted SnOsub.2 films. In addition, we report a strong chemical effect of ethanol on the FMR spectra. The obtained results are discussed within the model of two magnetic layers, with different concentrations and valence states of the implanted cobalt, and with a high content of oxygen vacancies.
Magnetic nanoparticles embedded into semiconductors have current perspectives for use in semiconducting spintronics. In this work, 40 keV Fesup.+ ions were implanted in high fluences of (0.5 ÷ 1.5) × ...10sup.17 ion/cmsup.2 into an oxide semiconductor and single-crystalline TiOsub.2 plates of rutile structure with (100) or (001) face orientations. Microstructure, elemental-phase composition, and magnetic properties of the Fe-ion-implanted TiOsub.2 were studied by scanning and transmission electron microscopies (SEM and TEM), X-ray photoelectron (XPS) and Rutherford backscattering (RBS) spectroscopies, as well as vibrating-sample magnetometry (VSM). The high-fluence ion implantation results in the formation of magnetic nanoparticles of metallic iron beneath the irradiated surface of rutile. The induced ferromagnetism and observed two- or four-fold magnetic anisotropy are associated with the endotaxial growth of Fe nanoparticles oriented along the crystallographic axes of TiOsub.2.
We present the results of ab initio studies of the structural and magnetic properties of the Pd host matrix doped by Fe atoms at various concentrations. By means of the density functional theory, we ...deduce that iron impurities are able to initialize significant magnetization of the Pd atoms, when the impurity concentration exceeds 3 at.%. We also demonstrate that the induced magnetization depends on impurity positions in the host matrix, in particular, there is a maximum of magnetization for a uniform distribution of the iron solute.
The doping of near-surface region of single crystalline p-type Si by Fe impurity under irradiation by the low-energy and high-current Xe+ ion beam is investigated. The recoil-atom implantation method ...was applied which utilizes simultaneous sputtering of Fe target with irradiation of the deposited Fe atoms on the Si substrate surface by Xe+ ion beam. The resulting incorporation of Fe atoms into Si leads to formation of very thin (~5 nm) highly doped (>1022 at/cm3) surface layer (Si:Fe) containing Si and α-Fe nanoparticles with sizes of 5–20 nm. Such a layer demonstrates ferromagnetism at T = 10 K and superparamagnetism at 300 K. Inversion of the conductivity type (from p-to n-type) in the heavily doped Si:Fe layer and formation of n-p junction to the substrate is observed. A photoresponse of thus obtained n-Si:Fe/p-Si diode structure demonstrates an intense signal in the wavelength range of 500–1200 nm with a maximum at about 950 nm under the low reverse bias voltage (U = 1 V), whose integral intensity is comparable with that for commercial silicon photodiode at U = 10 V.
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