APL Nameplate
  • Volume/Page
  • Keyword
  • DOI
  • Citation
  • Advanced
   
 
 
 

Flickr Twitter iResearch App Facebook

BROWSE VOLUMES

Year Range: 
Search Issue | RSS Feeds RSS
Previous Issue Next Issue

26 May 2003

Volume 82, Issue 21, pp. 3587-3793

Issue Cover Spotlight Figure

Appl. Phys. Lett. 82, 3716 (2003); http://dx.doi.org/10.1063/1.1577808 (3 pages)

V. Novosad, M. Grimsditch, J. Darrouzet, J. Pearson, S. D. Bader, V. Metlushko, K. Guslienko, Y. Otani, H. Shima, and K. Fukamichi
Enlarge Image | Read More
Page 2 of 3 Pages Previous Page Next Page | Jump to Page
back to top
RSS Feeds

Hydrogen-induced improvements in optical quality of GaNAs alloys

I. A. Buyanova, M. Izadifard, W. M. Chen, A. Polimeni, M. Capizzi, H. P. Xin, and C. W. Tu

Appl. Phys. Lett. 82, 3662 (2003); http://dx.doi.org/10.1063/1.1578513 (3 pages) | Cited 23 times

Online Publication Date: 20 May 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Strong suppression of potential fluctuations in the band edges of GaNAs alloys due to postgrowth hydrogen treatment, which is accompanied by a reopening of the alloy band gap, is revealed from temperature-dependent photoluminescence (PL) and PL excitation measurements. The effect likely indicates preferential trapping of hydrogen near the lattice sites with the highest nitrogen content. A remarkable improvement in the radiative efficiency of the alloys at room temperature is also demonstrated and is ascribed to efficient hydrogen passivation of competing nonradiative centers. © 2003 American Institute of Physics.
Show PACS
78.55.Cr III-V semiconductors
71.55.Eq III-V semiconductors
71.20.Nr Semiconductor compounds
78.67.De Quantum wells
78.66.Fd III-V semiconductors
73.21.Fg Quantum wells

Increasing medium-range order in amorphous silicon with low-energy ion bombardment

J. E. Gerbi, P. M. Voyles, M. M. J. Treacy, J. M. Gibson, and J. R. Abelson

Appl. Phys. Lett. 82, 3665 (2003); http://dx.doi.org/10.1063/1.1578164 (3 pages) | Cited 22 times

Online Publication Date: 20 May 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We have observed the existence of medium–range order in amorphous silicon with the fluctuation electron microscopy technique. We hypothesize that this structure is produced during the highly nonequilibrium deposition process, during which nuclei are formed and subsequently buried. We test this hypothesis by altering the deposition kinetics during magnetron sputter deposition by bombarding the growth surface with a variable flux of low-energy (20 eV) Ar+ ions. We observe that medium–range order increases monotonically as the ion/neutral flux ratio increases. We suggest that this low-energy bombardment increases adspecie surface mobility or modifies local structural rearrangements, resulting in enhanced medium–range order via increases in the size, volume fraction, and/or internal order of the nuclei. © 2003 American Institute of Physics.
Show PACS
61.43.Dq Amorphous semiconductors, metals, and alloys
61.80.Jh Ion radiation effects
61.82.Fk Semiconductors
81.05.Gc Amorphous semiconductors
68.55.-a Thin film structure and morphology
81.15.Cd Deposition by sputtering
back to top
RSS Feeds

Ultrafast carrier and plasmon-phonon dynamics in ion-irradiated n-GaAs

Muneaki Hase, Kunie Ishioka, Masahiro Kitajima, and Kiminori Ushida

Appl. Phys. Lett. 82, 3668 (2003); http://dx.doi.org/10.1063/1.1578179 (3 pages) | Cited 12 times

Online Publication Date: 20 May 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Ultrafast dynamics of plasmon-phonon coupled modes and photoexcited carriers in He ion irradiated n-GaAs has been investigated with a femtosecond pump-probe technique. The frequencies of the coupled modes shift as the ion dose increases, and after 1.9×1013 He+/cm2 irradiation the coherent oscillation of the coupled modes disappear. The relaxation time of the photoexcited carriers decreases with increasing ion dose, which is explained quantitatively by trapping of carriers via the deep levels related to single vacancies. The dose dependence of the dephasing time of the coupled modes and the relaxation time of the photoexcited carriers reveal that the trapping of the majority carriers dominates the disappearance as well as the frequency shift of the coupled mode oscillation. © 2003 American Institute of Physics.
Show PACS
71.55.Eq III-V semiconductors
71.45.Gm Exchange, correlation, dielectric and magnetic response functions, plasmons
61.80.Jh Ion radiation effects
61.82.Fk Semiconductors

Deep level defect in Si-implanted GaN n+-p junction

X. D. Chen, Y. Huang, S. Fung, C. D. Beling, C. C. Ling, J. K. Sheu, M. L. Lee, G. C. Chi, and S. J. Chang

Appl. Phys. Lett. 82, 3671 (2003); http://dx.doi.org/10.1063/1.1578167 (3 pages) | Cited 6 times

Online Publication Date: 20 May 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
A deep level transient spectroscopy (DLTS) study has been performed on a GaN n+-p junction fabricated by implanting Si into a Mg-doped p-type GaN epilayer. A high concentration of a deep level defect has been revealed within the interfacial region of the junctions by the unusual appearance of a minority peak in the majority carrier DLTS spectra. The deep level defect appears to be an electron trap at EC-0.59 eV in the p-side region of the junction and has tentatively been attributed to the VN–Mg complex. The high concentration of this electrically active deep level defect in the depletion layer of the Si-implanted GaN n+-p junction diodes suggests the need for further investigations. © 2003 American Institute of Physics.
Show PACS
73.20.Hb Impurity and defect levels; energy states of adsorbed species
73.40.Kp III-V semiconductor-to-semiconductor contacts, p-n junctions, and heterojunctions
73.50.Gr Charge carriers: generation, recombination, lifetime, trapping, mean free paths
61.72.Yx Interaction between different crystal defects; gettering effect

Direction-dependent band nonparabolicity effects on high-field transient electron transport in GaN

M. Wraback, H. Shen, S. Rudin, E. Bellotti, M. Goano, J. C. Carrano, C. J. Collins, J. C. Campbell, and R. D. Dupuis

Appl. Phys. Lett. 82, 3674 (2003); http://dx.doi.org/10.1063/1.1577833 (3 pages) | Cited 15 times

Online Publication Date: 20 May 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Time-resolved electroabsorption measurements on an AlGaN/GaN heterojunction p–i–n diode provide evidence of electron velocity overshoot at fields as low as ∼130 kV/cm for transport in the c-direction of wurtzite GaN. Theoretical Monte Carlo calculations employing a full band structure indicate that at fields below ∼300 kV/cm, this velocity overshoot is associated primarily with band nonparabolicity in the Γ valley related to a negative electron effective mass rather than intervalley transfer. Similar calculations of transport in the basal plane indicate that in this case, both a higher threshold field for velocity overshoot and a lower steady-state velocity at a given field are expected. © 2003 American Institute of Physics.
Show PACS
85.60.Dw Photodiodes; phototransistors; photoresistors
73.40.Kp III-V semiconductor-to-semiconductor contacts, p-n junctions, and heterojunctions
73.20.At Surface states, band structure, electron density of states
72.20.Ht High-field and nonlinear effects
78.20.Jq Electro-optical effects
78.47.-p Spectroscopy of solid state dynamics
71.18.+y Fermi surface: calculations and measurements; effective mass, g factor

Interface defects responsible for negative-bias temperature instability in plasma-nitrided SiON/Si(100) systems

Shinji Fujieda, Yoshinao Miura, Motofumi Saitoh, Eiji Hasegawa, Shin Koyama, and Koichi Ando

Appl. Phys. Lett. 82, 3677 (2003); http://dx.doi.org/10.1063/1.1578535 (3 pages) | Cited 21 times

Online Publication Date: 20 May 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Interface defects generated by negative-bias temperature stress (NBTS) in an ultrathin plasma- nitrided SiON/Si(100) system were characterized by using D2 annealing, conductance-frequency measurements, and electron-spin resonance measurements. D2 annealing was shown to lower negative-bias temperature instability (NBTI) than H2 annealing. Interfacial Si dangling bonds (Pb1 and Pb0 centers), whose density is comparable to an increase in interface trap density, were detected in a NBTS-stressed sample. The NBTI of the plasma-nitrided SiON/Si system was thus shown to occur through Pb depassivation. Furthermore, the nitridation was shown to increase the Pb1/Pb0 density ratio and modify the Pb1 structure. Such a predominance and structural modification of Pb1 centers are presumed to increase NBTI by enhancing the Pb–H dissociation. Although we suggest that NBTS may also induce non-Pb defects, nitrogen dangling bonds do not seem to be included in them. © 2003 American Institute of Physics.
Show PACS
73.20.Hb Impurity and defect levels; energy states of adsorbed species
73.40.Qv Metal-insulator-semiconductor structures (including semiconductor-to-insulator)
81.65.Lp Surface hardening: nitridation, carburization, carbonitridation
76.30.Mi Color centers and other defects
61.72.Cc Kinetics of defect formation and annealing
52.77.Bn Etching and cleaning

Cathodoluminescence studies of the electron injection-induced effects in GaN

Leonid Chernyak, William Burdett, Mikhail Klimov, and Andrei Osinsky

Appl. Phys. Lett. 82, 3680 (2003); http://dx.doi.org/10.1063/1.1578514 (3 pages) | Cited 7 times

Online Publication Date: 20 May 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Local irradiation of p-type GaN with the electron beam of a scanning electron microscope resulted in up to a threefold decrease of the peak cathodoluminescence intensity at ∼379 nm, as was observed in the variable temperature measurements. The cathodoluminescence results are consistent with an increase of the minority carrier diffusion length in the material, as is evident from the electron-beam-induced current measurements. The activation energy for the electron injection effect, estimated from the temperature-dependent cathodoluminescence, is in agreement with the thermal ionization energy of the Mg-acceptor in GaN. © 2003 American Institute of Physics.
Show PACS
78.60.Hk Cathodoluminescence, ionoluminescence
72.20.Jv Charge carriers: generation, recombination, lifetime, and trapping
71.55.Eq III-V semiconductors
72.80.Ey III-V and II-VI semiconductors

Metalorganic chemical vapor deposition of highly conductive Al0.65Ga0.35N films

P. Cantu, S. Keller, U. K. Mishra, and S. P. DenBaars

Appl. Phys. Lett. 82, 3683 (2003); http://dx.doi.org/10.1063/1.1577410 (3 pages) | Cited 16 times

Online Publication Date: 20 May 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Highly conductive Al0.65Ga0.35N films were fabricated using indium–silicon codoping and a low growth temperature of 920 °C in the metalorganic chemical vapor deposition process. The Al0.65Ga0.35N:(Si,In) layers exhibited an n-type carrier density as high as 2.5×1019 cm−3 with an electron mobility of 22 cm2/V s, corresponding to a resistivity of 1.1×10−4 Ω cm. Significantly higher resistivity values were measured for AlxGa1−xN:Si doped films with x⩾0.49 deposited at 1150 °C without indium, e.g., the Al0.62Ga0.38N:Si samples exhibited a maximum carrier concentration of 1.3×1017 cm−3 and a resistivity of 6.2×10−2 Ω cm. The electrical properties of the films are discussed in relation to the chemical concentrations of silicon and residual impurities in the films. © 2003 American Institute of Physics.
Show PACS
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
73.61.Ey III-V semiconductors
81.05.Ea III-V semiconductors
61.72.uj III-V and II-VI semiconductors
68.55.Ln Defects and impurities: doping, implantation, distribution, concentration, etc.

Electron spin relaxation under drift in GaAs

E. A. Barry, A. A. Kiselev, and K. W. Kim

Appl. Phys. Lett. 82, 3686 (2003); http://dx.doi.org/10.1063/1.1578180 (3 pages) | Cited 22 times

Online Publication Date: 20 May 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Based on a Monte Carlo method, we investigate the influence of transport conditions on the electron spin relaxation in GaAs. The decay of initial electron spin polarization is calculated as a function of distance under the presence of moderate drift fields and/or nonzero injection energies. For relatively low fields (a couple of kV/cm), a substantial amount of spin polarization is preserved for several microns at 300 K. However, it is also found that the spin relaxation rate increases rapidly with the drift field, scaling as the square of the electron wave vector in the direction of the field. When the electrons are injected with a high energy, a pronounced decrease is observed in the spin relaxation length due to an initial increase in the spin precession frequency. Hence, high-field or high-energy transport conditions may not be desirable for spin-based devices. © 2003 American Institute of Physics.
Show PACS
75.47.Pq Other materials
72.20.Jv Charge carriers: generation, recombination, lifetime, and trapping
72.80.Ey III-V and II-VI semiconductors

Doping-induced strain in N-doped 4H–SiC crystals

H. Jacobson, J. Birch, C. Hallin, A. Henry, R. Yakimova, T. Tuomi, E. Janzén, and U. Lindefelt

Appl. Phys. Lett. 82, 3689 (2003); http://dx.doi.org/10.1063/1.1579120 (3 pages) | Cited 11 times

Online Publication Date: 20 May 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Stress in epitaxial layers due to crystal lattice mismatch directly influences the growth, structure, and basic electrophysical parameters of epitaxial films and also to a large extent the degradation processes in semiconductor devices. In this letter, we present a theoretical model for calculating the induced lattice compression due to N doping and the critical thickness concerning formation of misfit dislocations in homoepitaxial 4H–SiC layers with different N-doping levels. For example: The model predicts that substrates with a N concentration of 3×1019 cm−3 induce misfit dislocations when the epilayer thickness reaches ∼ 10 μm. Also, the N-doping concentration in the 1×1018–1×1019 cm−3 range yields a strain that not will cause misfit dislocactions at the substrate and epilayer interface until an epilayer thickness of 200–300 μm is reached. Supporting evidence of the induced lattice compression due to N doping have been done by synchrotron white-beam x-ray topography on samples with different N-doping levels and are compared with the predicted results from the model. © 2003 American Institute of Physics.
Show PACS
68.60.Bs Mechanical and acoustical properties
68.55.-a Thin film structure and morphology
61.72.S- Impurities in crystals
62.20.-x Mechanical properties of solids

Nitride microlens arrays for blue and ultraviolet wavelength applications

T. N. Oder, J. Shakya, J. Y. Lin, and H. X. Jiang

Appl. Phys. Lett. 82, 3692 (2003); http://dx.doi.org/10.1063/1.1579872 (3 pages) | Cited 22 times

Online Publication Date: 20 May 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Nitride microlens arrays with sizes as small as 10 μm in diameter have been fabricated on GaN and AlN epilayers using the method of photoresist reflow and inductively coupled plasma dry etching. The focal lengths of the microlenses varied from 7–30 μm as determined by theoretical fitting as well as by the near-field scanning optical microscopy measurement. Scanning electron and atomic force microscopies were used to obtain the surface profile of the microlenses which were found to match very well with hemispherical fitting and a surface roughness value around 1 nm was obtained. Nitride microlens arrays would be naturally chosen for green/blue to deep ultraviolet wavelength applications. In addition, nitride microlenses offer the possibility of integrating nitride-based microsize photonic devices as well as of coupling light into, out of, and between arrays of III-nitride emitters for other applications, such as spatially resolved fluorescence spectroscopy studies of biological and medical systems and optical links, thereby further expanding the applications of III nitrides. © 2003 American Institute of Physics.
Show PACS
42.79.Bh Lenses, prisms and mirrors
back to top
RSS Feeds

Magnetic domain structure in a ferromagnetic shape memory alloy Ni51Fe22Ga27 studied by electron holography and Lorentz microscopy

Y. Murakami, D. Shindo, K. Oikawa, R. Kainuma, and K. Ishida

Appl. Phys. Lett. 82, 3695 (2003); http://dx.doi.org/10.1063/1.1578516 (3 pages) | Cited 34 times

Online Publication Date: 20 May 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Behaviors of magnetic domains with cooling in a Ni51Fe22Ga27 ferromagnetic shape memory alloy were examined by electron holography and Lorentz microscopy. A peculiar meshy pattern was observed in the Lorentz microscope image of the parent phase, being concurrent with the anomaly in the thermomagnetization curve. The meshy pattern was found to stem from the heavily bent lines of magnetic flux. The dramatic change in the magnetic domains is presumably due to some intrinsic magnetic instability that is pronounced by cooling, rather than a phenomenon triggered by the lattice modulation as the precursor effect of martensitic transformations or formation of the intermediate phase as observed in other systems. © 2003 American Institute of Physics.
Show PACS
75.50.Bb Fe and its alloys
75.60.Ch Domain walls and domain structure
81.30.Kf Martensitic transformations
64.70.K- Solid-solid transitions
75.60.Ej Magnetization curves, hysteresis, Barkhausen and related effects
61.05.jp Electron holography

Correlation between fractal dimension and reversal behavior of magnetic domain in Co/Pd nanomultilayers

Dong-Hyun Kim, Yoon-Chul Cho, Sug-Bong Choe, and Sung-Chul Shin

Appl. Phys. Lett. 82, 3698 (2003); http://dx.doi.org/10.1063/1.1578185 (3 pages) | Cited 6 times

Online Publication Date: 20 May 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We report the experimental finding that there is a close correlation between fractal geometry and reversal mechanism of magnetic domain in Co/Pd nanomultilayers. We have measured the fractal dimension Df of magnetic domain as well as the wall-motion speed V, the nucleation rate R, and the reversal ratio V/R in Co/Pd nanomultilayer films during magnetization reversal via time-resolved direct domain observation. Interestingly enough, Df is inversely related to the reversal ratio V/R, which could be quantitatively explained using a micromagnetic simulation based on thermally activated relaxation model. We find that the fractal dimension is a crucial parameter to characterize magnetization reversal behavior as well as jaggedness of domain geometry. © 2003 American Institute of Physics.
Show PACS
75.70.Cn Magnetic properties of interfaces (multilayers, superlattices, heterostructures)
75.50.Cc Other ferromagnetic metals and alloys
75.60.Jk Magnetization reversal mechanisms
75.70.Kw Domain structure (including magnetic bubbles and vortices)
75.50.Tt Fine-particle systems; nanocrystalline materials

The energy barriers in antiferromagnetically coupled media

D. T. Margulies, A. Berger, A. Moser, M. E. Schabes, and Eric E. Fullerton

Appl. Phys. Lett. 82, 3701 (2003); http://dx.doi.org/10.1063/1.1578161 (3 pages) | Cited 12 times

Online Publication Date: 20 May 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We study the physics of the energy barriers for magnetization reversal in antiferromagnetically coupled (AFC) media by means of temperature dependent magnetometry as well as modeling. We find that the energy barrier of the lower layer is fairly low, and mainly given by its anisotropy–volume product (KV). This means the lower layer magnetization is actually in thermal equilibrium, but the presence of the interlayer coupling makes the state with AF alignment of both layers thermodynamically so much more probable, that AFC media are thermally stable overall. The model further predicts that for typical values of the exchange coupling constant, the energy barrier of the composite system at zero field is essentially equal to the upper layer KV with the additional energy from the interlayer coupling being only a small perturbation. © 2003 American Institute of Physics.
Show PACS
75.50.Ss Magnetic recording materials
75.60.Jk Magnetization reversal mechanisms
75.30.Gw Magnetic anisotropy
75.30.Et Exchange and superexchange interactions
75.50.Ee Antiferromagnetics

Fabrication of a vector Hall sensor for magnetic microscopy

D. Gregušová, V. Cambel, J. Fedor, R. Kúdela, J. Šoltýs, T. Lalinský, I. Kostič, and S. J. Bending

Appl. Phys. Lett. 82, 3704 (2003); http://dx.doi.org/10.1063/1.1577820 (3 pages) | Cited 9 times

Online Publication Date: 20 May 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We have developed a micromachined Hall sensor for scanning the entire magnetic field vector whose active dimensions are an order of magnitude smaller (∼5 μm) than the smallest existing vector field sensor. It is realized by patterning three Hall probes on the tilted faces of epitaxy-overgrown GaAs-based pyramidal-shaped mesa structures. Data from these “tilted” Hall probes are used to reconstruct the full magnetic field vector. © 2003 American Institute of Physics.
Show PACS
07.07.Df Sensors (chemical, optical, electrical, movement, gas, etc.); remote sensing

Magnetic properties and magneto-optical effect of Co0.5Fe2.5O4 nanostructured films

B. X. Gu

Appl. Phys. Lett. 82, 3707 (2003); http://dx.doi.org/10.1063/1.1573357 (3 pages) | Cited 8 times

Online Publication Date: 20 May 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Co0.5Fe2.5O4 ferrite films with nanostructure have been prepared by rf sputtering on a quartz substrate and annealed at temperatures from 400 to 600 °C in air. The magnetic properties and magneto-optical effect have been studied. It has been found that nanocrystalline Co0.5Fe2.5O4 films exhibit good magnetic properties and a large magneto-optical effect. The magnetization, coercivity, remanence ratio, and maximum energy product are 455 emu/cm3, 2.8 kOe, 0.72 MGOe, and 2.4 MGOe, respectively. The magneto-optical Faraday rotation is <−3.4°/μm at short wavelength and 4°/μm at the wavelength of 740 nm. These characteristics make them very promising to be used for magneto-optical recording and for permanent magnets. The influence of the distribution of Co2+ ions on magnetic properties and magneto-optical effect has been discussed. © 2003 American Institute of Physics.
Show PACS
75.50.Gg Ferrimagnetics
78.20.Ls Magneto-optical effects
75.70.Ak Magnetic properties of monolayers and thin films
75.50.Tt Fine-particle systems; nanocrystalline materials
75.60.Ej Magnetization curves, hysteresis, Barkhausen and related effects
75.50.Vv High coercivity materials
81.40.Rs Electrical and magnetic properties related to treatment conditions

Intrinsic and extrinsic properties of epitaxial Nd2Fe14B films

Ullrich Hannemann, Sebastian Fähler, Volker Neu, Bernhard Holzapfel, and Ludwig Schultz

Appl. Phys. Lett. 82, 3710 (2003); http://dx.doi.org/10.1063/1.1576913 (3 pages) | Cited 18 times

Online Publication Date: 20 May 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Epitaxial Nd2Fe14B films with the c axis (easy magnetization axis) perpendicular to the film plane were prepared on a Ta(110) buffer on single crystalline Al2O3(0001) substrates using pulsed laser deposition. Due to the epitaxial film growth an almost perfect alignment of all magnetic moments perpendicular to the film plane is achieved. Coercivities up to 2 T are obtained for Nd-rich films where the Nd2Fe14B grains are magnetically decoupled. An analysis of the coercivity mechanism shows that the switching mechanism is nucleation dominated and the high coercivity is achieved by avoiding nucleation within the grains. Intrinsic properties like the spin reorientation temperature of 135 K and spin reorientation angle of 30° at 4.2 K of these films are in very good agreement to single crystal data. © 2003 American Institute of Physics.
Show PACS
75.70.-i Magnetic properties of thin films, surfaces, and interfaces
75.60.Ej Magnetization curves, hysteresis, Barkhausen and related effects
75.30.Wx Spin crossover
75.30.Cr Saturation moments and magnetic susceptibilities

High magnetic field sensor using LaSb2

D. P. Young, R. G. Goodrich, J. F. DiTusa, S. Guo, P. W. Adams, Julia Y. Chan, and Donavan Hall

Appl. Phys. Lett. 82, 3713 (2003); http://dx.doi.org/10.1063/1.1577390 (3 pages) | Cited 14 times

Online Publication Date: 20 May 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The magnetotransport properties of single crystals of the highly anisotropic layered metal LaSb2 are reported in magnetic fields up to 45 T with fields oriented both parallel and perpendicular to the layers. Below 10 K the perpendicular magnetoresistance of LaSb2 becomes temperature independent and is characterized by a 100-fold linear increase in resistance between 0 and 45 T with no evidence of quantum oscillations down to 50 mK. The Hall resistivity is hole-like and gives a high field carrier density of n ∼ 3×1020 cm−3. The feasibility of using LaSb2 for magnetic field sensors is discussed. © 2003 American Institute of Physics.
Show PACS
75.47.Pq Other materials
07.07.Df Sensors (chemical, optical, electrical, movement, gas, etc.); remote sensing
07.55.Ge Magnetometers for magnetic field measurements
75.47.De Giant magnetoresistance
72.20.My Galvanomagnetic and other magnetotransport effects
85.75.Nn Hybrid Hall devices
75.30.Gw Magnetic anisotropy

Shape effect on magnetization reversal in chains of interacting ferromagnetic elements

V. Novosad, M. Grimsditch, J. Darrouzet, J. Pearson, S. D. Bader, V. Metlushko, K. Guslienko, Y. Otani, H. Shima, and K. Fukamichi

Appl. Phys. Lett. 82, 3716 (2003); http://dx.doi.org/10.1063/1.1577808 (3 pages) | Cited 33 times

Online Publication Date: 20 May 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The magnetization reversal in the chains of submicron square- and disk-shaped Permalloy dots with lateral size of 800 nm, thickness of 50 nm and variable inter dot distance was investigated by using the magneto-optical Kerr effect technique, magnetic force microscopy and micromagnetic modeling. We have found that the particle shape strongly affects the characteristic switching fields of well-separated dots, and has almost no influence on strength of inter dot interaction in chains of magnetostatically coupled elements. © 2003 American Institute of Physics.
Show PACS
75.60.Jk Magnetization reversal mechanisms
75.50.Bb Fe and its alloys
75.75.-c Magnetic properties of nanostructures
75.50.Tt Fine-particle systems; nanocrystalline materials
75.70.Cn Magnetic properties of interfaces (multilayers, superlattices, heterostructures)
78.20.Ls Magneto-optical effects
68.37.Rt Magnetic force microscopy (MFM)
75.30.Et Exchange and superexchange interactions

Optical detection of electron paramagnetic resonance in CdMnTe single quantum wells

M. L. Sadowski, M. Byszewski, M. Potemski, A. Sachrajda, and G. Karczewski

Appl. Phys. Lett. 82, 3719 (2003); http://dx.doi.org/10.1063/1.1578511 (3 pages) | Cited 5 times

Online Publication Date: 20 May 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The electron paramagnetic resonance of Mn2+ ions localized in a CdTe quantum well is measured by an all-optical method. The photoluminescence transitions of a two-dimensional electron gas are used to monitor changes in the Mn spin polarization. The local character of this probe and the detection technique permit us to achieve a very high sensitivity for the number of spins detected (better than 108 spins). Two simultaneous effects are observed at resonance: A blueshift of the whole photoluminescence spectrum, and a dramatic transfer of photoluminescence intensity from neutral to negatively charged excitons. © 2003 American Institute of Physics.
Show PACS
76.70.Hb Optically detected magnetic resonance (ODMR)
78.67.De Quantum wells
73.21.Fg Quantum wells
75.50.Pp Magnetic semiconductors
78.55.Hx Other solid inorganic materials
71.35.Pq Charged excitons (trions)

Approach to optimize the pinning effect of a NiMn layer with reduced thickness under a much shortened annealing process

B. Dai, J. W. Cai, W. Y. Lai, F. Shen, Z. Zhang, and G. H. Yu

Appl. Phys. Lett. 82, 3722 (2003); http://dx.doi.org/10.1063/1.1579118 (3 pages) | Cited 5 times

Online Publication Date: 20 May 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We investigated the magnetic properties of sputtered Ni0.8Fe0.2/Ni1−xMnx (0.43 ⩽ x ⩽ 0.70) bilayers and found that an antiferromagnetic equiatomic NiMn layer could be formed through Mn diffusion with reduced thickness and a much shortened annealing time if the Ni1−xMnx layer is off-stoichiometric with suitable excess Mn. An overdose of Mn in a NiMn precursor layer was demonstrated to enhance the migration and the diffusion of Mn atoms, which seemed to promote the formation of antiferromagnetic NiMn of the θ phase, but in the mean time led to the deterioration of the adjacent ferromagnetic layer. We thus introduced the nano-oxide layer in the ferromagnetic layer near the interface of ferromagnetic and antiferromagnetic layers, which was proven to be very efficient to prevent Mn atoms from further intruding into the ferromagnetic layer even in the case that a large amount of Mn atoms were involved. As a result, a ferromagnetic layer pinned by a NiMn layer with excellent performance has been developed in a much simplified process. © 2003 American Institute of Physics.
Show PACS
75.50.Ee Antiferromagnetics
75.70.Ak Magnetic properties of monolayers and thin films
75.30.Et Exchange and superexchange interactions
61.72.Cc Kinetics of defect formation and annealing

Dynamically tuning properties of epitaxial colossal magnetoresistance thin films

Darren Dale, Aaron Fleet, J. D. Brock, and Y. Suzuki

Appl. Phys. Lett. 82, 3725 (2003); http://dx.doi.org/10.1063/1.1578186 (3 pages) | Cited 35 times

Online Publication Date: 20 May 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The strain state of epitaxial La0.5Sr0.5MnO3 thin films on BaTiO3 are dynamically tuned by temperature and substrate bias. The resistivity of the La0.5Sr0.5MnO3 thin films is particularly sensitive to changes in structure. Fractional changes in magnetization and resistivity as a function of temperature reveal a direct correlation with fractional changes in the structure, as measured by out-of-plane x-ray diffraction. Fractional changes in resistivity, as large as 30%, are observed for strain induced by the structural phase transitions of the BaTiO3 substrate, and a 12% change is induced by an inverse piezoelectric effect at room temperature. © 2003 American Institute of Physics.
Show PACS
75.47.Lx Magnetic oxides
75.47.Gk Colossal magnetoresistance
75.50.Dd Nonmetallic ferromagnetic materials
75.70.Ak Magnetic properties of monolayers and thin films
68.60.Bs Mechanical and acoustical properties
75.60.Ej Magnetization curves, hysteresis, Barkhausen and related effects
68.55.-a Thin film structure and morphology
77.65.Ly Strain-induced piezoelectric fields

Detwinning YBa2Cu3O7−δ thin films

J. Nam, R. A. Hughes, A. Dabkowski, and J. S. Preston

Appl. Phys. Lett. 82, 3728 (2003); http://dx.doi.org/10.1063/1.1578166 (3 pages) | Cited 4 times

Online Publication Date: 20 May 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Single crystals of YBa2Cu3O7-δ (YBCO) have been detwinned under the simultaneous application of heat and uniaxial stress. This approach, however, has proved futile in thin films as they become heavily twinned due to strain from the underlying substrate as well as the orthorhombic unit cell. This lack of control over twinning has made it difficult to determine the role that twins play in determining the transport properties of films. Here, we present a technique for detwinning YBCO thin films. The detwinning in YBCO thin film is achieved by suspending a portion of the YBCO film above the underlying substrate. The suspended material is no longer influenced by the confining effects of the substrate and this allows it to detwin under the application of a uniaxial stress brought about by an anneal. With this technique, we are able to produce high-quality detwinned regions that will help aid the understanding of transport mechanisms in YBCO. © 2003 American Institute of Physics.
Show PACS
74.72.-h Cuprate superconductors
74.78.-w Superconducting films and low-dimensional structures
74.62.Bf Effects of material synthesis, crystal structure, and chemical composition
61.72.Mm Grain and twin boundaries

Uniaxial magnetic anisotropy and magnetic switching in La0.67Sr0.33MnO3 thin films grown on vicinal SrTiO3(100)

Zhi-Hong Wang, G. Cristiani, and H.-U. Habermeier

Appl. Phys. Lett. 82, 3731 (2003); http://dx.doi.org/10.1063/1.1578711 (3 pages) | Cited 31 times

Online Publication Date: 20 May 2003

Full Text: Read Online (HTML) | Download PDF


See Also: Publisher's Note

Show Abstract
La0.67Sr0.33MnO3 ultrathin films grown on vicinal SrTiO3(100) surface show an in-plane uniaxial magnetic anisotropy with easy axis along the substrate atomic steps generated by a 10° miscut off the (100) plane. Over a large angular range, the angular dependence of magnetic switching field is found to obey the 1/cos φ law, indicating that the magnetic reversal is completed by a 180° domain nucleation and sweeping along the easy axis. However, when the applied field is perpendicular to the hard axis (φ = 90°), the magnetization reversal is found to be well described by the Stoner–Wohlfarth model, in which the magnetization coherently rotates from the easy axis to hard axis. © 2003 American Institute of Physics.
Show PACS
75.70.Ak Magnetic properties of monolayers and thin films
75.60.Jk Magnetization reversal mechanisms
75.30.Gw Magnetic anisotropy
75.50.Dd Nonmetallic ferromagnetic materials
75.47.Gk Colossal magnetoresistance
75.60.Ch Domain walls and domain structure
75.70.Kw Domain structure (including magnetic bubbles and vortices)
back to top
RSS Feeds

Dielectric properties of Bi2O3–ZnO–Ta2O5 pyrochlore and zirconolite structure ceramics

Chen Ang, Zhi Yu, H. J. Youn, C. A. Randall, A. S. Bhalla, L. E. Cross, and M. Lanagan

Appl. Phys. Lett. 82, 3734 (2003); http://dx.doi.org/10.1063/1.1575933 (3 pages) | Cited 11 times

Online Publication Date: 20 May 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
This letter reports the dielectric properties of the cubic pyrochlore (Bi3/4Zn1/4)2(Zn1/4Ta3/4)2O7, monoclinic zirconolite Bi2(Zn1/3Ta2/3)2O7, and their composites in the temperature range of 10–400 K from 102 to ∼ 1010 Hz. Composites with a near zero temperature coefficient of capacitance (TCC) consisting of the cubic pyrochlore and monoclinic zirconolite phases have been obtained. The observed microwave dielectric properties (ϵ=∼60, Q=∼325, and TCC=∼30 ppm/K at ∼5.1 GHz) as well as their low sintering temperatures (950–1100 °C) show that the compounds are promising materials for recently developed microwave devices, which demand that dielectric ceramics can be cofired with silver electrodes. © 2003 American Institute of Physics.
Show PACS
77.80.-e Ferroelectricity and antiferroelectricity
77.84.Ek Niobates and tantalates
77.84.Cg PZT ceramics and other titanates
77.22.Ch Permittivity (dielectric function)
77.22.Gm Dielectric loss and relaxation
81.20.Ev Powder processing: powder metallurgy, compaction, sintering, mechanical alloying, and granulation
Page 2 of 3 Pages Previous Page Next Page | Jump to Page
Close

Google Calendar

ADVERTISEMENT

Go to AIP Home   © AIP Publishing LLC
close