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This article introduces the October 2003 issue of MRS Bulletin on “New Materials for Spintronics.” As a result of quantum mechanics, the carriers in ferromagnetic metals such as Fe, Co, and Ni are spin-polarized due to an imbalance at the... more
This article introduces the October 2003 issue of MRS Bulletin on “New Materials for Spintronics.” As a result of quantum mechanics, the carriers in ferromagnetic metals such as Fe, Co, and Ni are spin-polarized due to an imbalance at the Fermi level in the number of spin-up and spin-down electrons. A carrier maintains its spin polarization as long as it does not encounter a magnetic impurity or interact with the host lattice by means of spin-orbit coupling. The discovery of optically induced, long-lived quantum coherent spin states in semiconductors has created a range of possibilities for a new class of devices that utilize spin. This discovery also points to the need for a wider range of spin-polarized materials that will be required for different device configurations. In this issue of MRS Bulletin, we focus on three classes of candidate spintronic materials and review the current state of our understanding of them: III–V and II–VI semiconductors, oxides, and Heusler alloys. The...
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... We use the results of these fits to obtain as a function of wavelength, and then calculatealpha . In Fig. alpha for both the thin and thick films is shown; notice that for energies under the values for the thin film are larger than... more
... We use the results of these fits to obtain as a function of wavelength, and then calculatealpha . In Fig. alpha for both the thin and thick films is shown; notice that for energies under the values for the thin film are larger than those for the thick film. ...
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Research Interests: Engineering, PHOTOELECTRON SPECTROSCOPY, Molecular beam epitaxy, Transition-Metal Oxides, Electromagnetic Radiation, and 12 morePhysical sciences, Band Gap, Low energy electron diffraction, Circuit Design, Space Charge, Ionizing Radiation, Charge Density, Charge transfer, Gain Control, X Ray Photoelectron Spectroscopy, Energy Levels, and Intermetallic Compound
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... Rev. B 52 (1995) 17449. [17] YJ Kim, Ph.D. Thesis, Department of Chemistry, Univer-sity of Hawaii, USA, 1995. I-18] HC Galloway, JJ Benitez and M. Salmeron, J. Vac. Sci. Technol. ... 1 81 (1985) 1263. 1-22] FC Voogt, T. Hibma, GL... more
... Rev. B 52 (1995) 17449. [17] YJ Kim, Ph.D. Thesis, Department of Chemistry, Univer-sity of Hawaii, USA, 1995. I-18] HC Galloway, JJ Benitez and M. Salmeron, J. Vac. Sci. Technol. ... 1 81 (1985) 1263. 1-22] FC Voogt, T. Hibma, GL Zhang, M. Hoefman and L Niesen, Surf. Sci. ...
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Research Interests: Engineering, Technology, Epitaxial Growth, Semiconductors, Molecular beam epitaxy, and 12 morePhysical sciences, Magnetic Properties, Curie temperature, Room Temperature, Single Crystal, Layer by Layer, Growth rate, Thin Solid Films, Titanium oxide, Material Properties, Dilute magnetic semiconductor, and uniform distribution
Research Interests: Engineering, Materials Science, Chemistry, Technology, Electron Diffraction, and 11 moreMolecular beam epitaxy, Scanning tunneling microscopy, Reactive Oxygen Species, Physical sciences, Surface Area, X ray diffraction, Three Dimensional, Thin Solid Films, X Ray Photoelectron Spectroscopy, Reflection High-Energy Electron Diffraction, and Growth mechanism
Research Interests: Engineering, Materials Science, Technology, Polymorphism, Titanium, and 14 moreMolecular beam epitaxy, Scanning tunneling microscopy, Ultraviolet, Thin Film, Titanium dioxide, The, CHEMICAL SCIENCES, High Resolution, Surface Structure, Anatase, Single Crystal, UV light, X Ray Photoelectron Spectroscopy, and Rate Constant
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... Electrons from these states may constitute the active ingredient in the increased photocatalytic activity observed for mixed Nb,O,/TiO, powders relative to pure TiO,. ... JF Baumard and E. Tani, J. Chem. Phys. 67 (1977) 857. SA... more
... Electrons from these states may constitute the active ingredient in the increased photocatalytic activity observed for mixed Nb,O,/TiO, powders relative to pure TiO,. ... JF Baumard and E. Tani, J. Chem. Phys. 67 (1977) 857. SA Chambers, TT Tran and TA Hileman. J. Mater. Res. ...
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Research Interests: Condensed Matter Physics, Materials Science, Quantum Physics, Chemistry, Surface Science, and 12 morePHOTOELECTRON SPECTROSCOPY, Atomic Force Microscopy, Molecular beam epitaxy, Thin Films, PT, Surface Reconstruction, Low energy electron diffraction, Thermal Stability, Titanium Oxides, Chemical Bonds, Titanium oxide, and Vacancy Defect
Research Interests: Materials Science, Transmission Electron Microscopy, Magnetic thin film, Magnetic field, Molecular beam epitaxy, and 14 moreThin Film, Physical sciences, Magnetic Properties, Energy Dispersive X-Ray Analysis, CHEMICAL SCIENCES, Curie temperature, Room Temperature, American physical society, Thin film deposition, High-Resolution X-Ray Diffraction, Hall effect, extended x-ray absorption fine structure (EXAFS), Spin Polarization, and Rutherford Backscattering Spectrometry
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We grew epitaxial α–Fe2O3(1010) on TiO2(001) rutile by oxygen plasma-assisted molecular-beam epitaxy. High-resolution transmission electron microscopy (HRTEM), reflection high-energy electron diffraction (RHEED), and x-ray diffraction... more
We grew epitaxial α–Fe2O3(1010) on TiO2(001) rutile by oxygen plasma-assisted molecular-beam epitaxy. High-resolution transmission electron microscopy (HRTEM), reflection high-energy electron diffraction (RHEED), and x-ray diffraction pole figures confirm that the film is composed of four different in-plane orientations rotated by 90° relative to one another. For a given Fe2O3 unit cell, the lattice mismatch along the parallel [0001]Fe2O3 and [100]TiO2 directions is nominally +67%. However, due to a 3-fold repetition of the slightly distorted square symmetry of anion positions within the Fe2O3 unit cell, there is a coincidental anion alignment along the [0001]Fe2O3 and [100]TiO2 directions, which results in an effective lattice mismatch of only −0.02% along this direction. The lattice mismatch is nearly 10% in the orthogonal [1120]Fe2O3 and [100]TiO2 directions. The film is highly ordered and well registered to the substrate despite a large lattice mismatch in one direction. The fil...
Research Interests: Materials Engineering, Mechanical Engineering, Condensed Matter Physics, Materials Science, Materials, and 9 moreTransmission Electron Microscopy, Electron Diffraction, Molecular beam epitaxy, High Resolution Transmission Electron Microscopy, Dislocations, Structure Analysis, X ray diffraction, Epitaxy, and Reflection High-Energy Electron Diffraction
Pure anatase TiO2 and CoxTi1-xO2 (0.01<x<0.04) epitaxial thin films were deposited by oxygen-plasma-assisted molecular beam epitaxy on Si(001) for evaluation as a potential dilute magnetic semiconductor material suitable for... more
Pure anatase TiO2 and CoxTi1-xO2 (0.01<x<0.04) epitaxial thin films were deposited by oxygen-plasma-assisted molecular beam epitaxy on Si(001) for evaluation as a potential dilute magnetic semiconductor material suitable for Si-based spintronic devices. Epitaxial growth on Si(001) was facilitated by the deposition of 1/4 or 1/2 ML Sr metal on the clean Si(001) surface to form an oxidation resistant silicide layer, followed by deposition of a thin SrTiO3 buffer layer. Using 1/2 ML Sr metal to form the silicide allowed the deposition of 10 ML SrTiO3 without oxidation of the Si interface. Epitaxial anatase could be grown on this heterostructure, although use of the oxygen plasma during deposition resulted in significant SiO2 formation. Pure anatase films consisted of epitaxial anatase surface particles on a continuous anatase film. For Co-doped films, Co segregation to surface particles of epitaxial anatase was observed by Auger electron spectroscopy and transmission electron microscopy (TEM); faceting of the particles was observed for low Co doping concentrations. Although no secondary phases containing Co were observed in Co-doped anatase films by x-ray diffraction or TEM, x-ray absorption near edge spectroscopy indicated Co was present in the films as a mixture of Co(0), Co(II), and Co(III). All samples were ferromagnetic at room temperature; for lower Co concentrations, the ferromagnetic remanence (9%) and coercive field (100 Oe) were similar to phase-pure Co:TiO2/LaAlO3. However, the presence of Co(0) under strongly oxidizing growth conditions known to oxidize the Si interface implies that under no deposition conditions can Co metal be eliminated while simultaneously protecting the Si interface from oxidation.
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ABSTRACT
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We have used plasma-assisted molecular beam epitaxy to synthesize structurally near-perfect crystalline films of TiO2−xNx rutile for the first time. These materials allow the properties of TiO2−xNx to be elucidated without the interfering... more
We have used plasma-assisted molecular beam epitaxy to synthesize structurally near-perfect crystalline films of TiO2−xNx rutile for the first time. These materials allow the properties of TiO2−xNx to be elucidated without the interfering effects of bulk substoichiometric defects that have characterized previous investigations. In the absence of such defects, the extent of N incorporation in the lattice is limited to
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We have used photoemission methods to directly measure the valence and conduction band offsets at SrTiO3/Si(001) interfaces, as prepared by molecular-beam epitaxy. Within experimental error, the measured values are the same for growth on... more
We have used photoemission methods to directly measure the valence and conduction band offsets at SrTiO3/Si(001) interfaces, as prepared by molecular-beam epitaxy. Within experimental error, the measured values are the same for growth on n- and p-Si, with the entire band discontinuity occurring at the valence band edge. In addition, band bending is much larger at the p-Si heterojunction than at the n-type heterojunction. Previously published threshold voltage behavior for these interfaces can now be understood in light of the present results.
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ABSTRACT
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Clusters and magnetism in epitaxial Co-doped TiO anatase. [Applied Physics Letters 82, 1257 (2003)]. SA Chambers, T. Droubay, CM Wang, AS Lea, RFC Farrow, L. Folks, V. Deline, S. Anders. Abstract. ... Magnetic properties of... more
Clusters and magnetism in epitaxial Co-doped TiO anatase. [Applied Physics Letters 82, 1257 (2003)]. SA Chambers, T. Droubay, CM Wang, AS Lea, RFC Farrow, L. Folks, V. Deline, S. Anders. Abstract. ... Magnetic properties of nanostructures. Body. ...
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... J. Kim, Mater. Today 5, 24 (2002). BT Jonker, YD Park, BR Bennett, HD Cheong, G. Kioseoglou, and A. Petrou, Robust electrical spin injection into a semiconductor heterostructure, Phys. Rev. B 62, 8180 (2000). YD Park, AT ...