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

1 Sep 2003

Volume 83, Issue 9, pp. 1689-1898

Issue Cover Spotlight Figure

Appl. Phys. Lett. 83, 1710 (2003); http://dx.doi.org/10.1063/1.1605792 (3 pages)

G. D. Chern, H. E. Tureci, A. Douglas Stone, R. K. Chang, M. Kneissl, and N. M. Johnson
Enlarge Image | Read More
Return to All Sections
back to top
RSS Feeds

FePt (001) texture development on an Fe–Ta–C magnetic soft underlayer with SiO2/MgO as an intermediate layer

Z. G. Zhang, K. Kang, and T. Suzuki

Appl. Phys. Lett. 83, 1785 (2003); http://dx.doi.org/10.1063/1.1606492 (3 pages) | Cited 30 times

Online Publication Date: 26 August 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
In order to develop the FePt (001) texture on an Fe–Ta–C magnetic soft underlayer (SUL), a combined SiO2/MgO intermediate layer is used between the SUL and FePt/MgO laminated recording layer. The function of the amorphous SiO2 layer is to cut the epitaxial growth relationship between the SUL and recording layer and to establish the MgO (200) texture. The thin FePt layers are epitaxially grown on the MgO layers and transformed into (001)-textured L10 FePt films upon annealing. Increasing the surface roughness of the Fe–Ta–C SUL from 0.74 to 2.35 nm does not significantly affect the FePt (001) texture, but has an effect on the FePt grain c-axis dispersion and the FePt L10 phase ordering. © 2003 American Institute of Physics.
Show PACS
75.70.Cn Magnetic properties of interfaces (multilayers, superlattices, heterostructures)
75.50.Ss Magnetic recording materials
68.65.Ac Multilayers
75.50.Bb Fe and its alloys
68.35.B- Structure of clean surfaces (and surface reconstruction)
61.72.Cc Kinetics of defect formation and annealing
81.40.Gh Other heat and thermomechanical treatments

Ordering oscillation of local composition in melt-processed REBa2Cu3O7−δ superconductors (RE: Sm, Eu, Gd)

A. Hu, M. Murakami, and H. Zhou

Appl. Phys. Lett. 83, 1788 (2003); http://dx.doi.org/10.1063/1.1605262 (3 pages) | Cited 23 times

Online Publication Date: 26 August 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
High quality melt-processed GdBa2Cu3O7−δ, (Sm0.5Eu0.5)Ba2Cu3O7−δ and (Sm0.33Eu0.33Gd0.33)Ba2Cu3O7−δ single domains were grown in air and the microstructural origin of their distinguished superconducting performance was investigated by a transmission electron microscope equipped with energy-dispersive spectroscopy. A periodic array of the chemical composition with tens of micrometer correlation was unveiled due to the spatial oscillation of RE (RE: Sm, Eu, and Gd) and Ba around the stoichiometric ratio with a nanometer scale wavelength. For (Sm0.5Eu0.5)Ba2Cu3O7−δ, the temperature dependence of the reversible magnetic moment at certain fields showed two kinks. The first transition followed three-dimensional scaling and yielded dBc2/dT = 1.98 T/K, corresponding to thermal fluctuation of the bulk superconductivity while the second displayed a linear temperature function with slightly lower Tc than bulk Tc and a slope of 0.6 T/K. This may indicate a field-induced pinning scenario with low Tc stripes. © 2003 American Institute of Physics.
Show PACS
74.62.Bf Effects of material synthesis, crystal structure, and chemical composition
61.66.Bi Elemental solids
61.66.Dk Alloys
74.72.-h Cuprate superconductors
74.25.Uv Vortex phases (includes vortex lattices, vortex liquids, and vortex glasses)
74.40.-n Fluctuation phenomena
74.25.Ha Magnetic properties including vortex structures and related phenomena

Electronic structure of cubic Li(Fe0.1Mn1.9)O4 studied with Mössbauer spectroscopy and first-principles calculation

Y. J. Wei, X. G. Xu, C. Z. Wang, C. Li, G. Chen, and F. Wu

Appl. Phys. Lett. 83, 1791 (2003); http://dx.doi.org/10.1063/1.1606494 (3 pages) | Cited 4 times

Online Publication Date: 26 August 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Mössbauer spectrum was collected in Fe3+ doped cubic LiMn2O4 (LiFe0.1Mn1.9O4) by using 57Fe as the radiation source. In the model of the crystal-field theory, the energy gaps between different d orbitals, ΔE(b1g−a1g) and ΔE(b2g−eg), characterize the strength of the Jahn–Teller effect in the crystal. A relationship between the Mössbauer quardrupole splitting and the energy gaps was established, based on which both ΔE(b1g−a1g) and ΔE(b2g−eg) of the [MnO6] octahedron in LiFe0.1Mn1.9O4 are estimated to be about 0.41 and 0.30 eV, respectively. Electronic structure of LiMn2O4 was studied theoretically via ab initio calculation based on the density-functional theory. Calculation shows that a gap about 0.28 eV between the filled Mn d bands is equivalent to ΔE(b2g−eg). It also shows that the first unoccupied states are dominated by Mn 3d contribution essentially from both a1g and b1g of Mn d states. Distance between the two peaks in the first unoccupied band was used to calculate ΔE(b1g−a1g), which is about 0.36 eV. The Mössbauer quardrupole splitting characterizes Jahn–Teller distortion and its effect on the fine structure of Mn 3d bands. © 2003 American Institute of Physics.
Show PACS
71.20.Ps Other inorganic compounds
76.80.+y Mössbauer effect; other γ-ray spectroscopy
71.15.Mb Density functional theory, local density approximation, gradient and other corrections
71.70.Ch Crystal and ligand fields
71.70.Ej Spin-orbit coupling, Zeeman and Stark splitting, Jahn-Teller effect
71.70.Jp Nuclear states and interactions

Thermal transport in stacked superconductor–normal metal–superconductor Josephson junctions

Yonuk Chong, P. D. Dresselhaus, and S. P. Benz

Appl. Phys. Lett. 83, 1794 (2003); http://dx.doi.org/10.1063/1.1606491 (3 pages) | Cited 14 times

Online Publication Date: 26 August 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Nb/MoSi2/Nb stacked superconductor–normal metal–superconductor (SNS) Josephson junctions has proven to be a good candidate for high-density series arrays for Josephson voltage-standard applications. As the junction density increases, self-heating becomes an issue because the high power density per junction (1 W/cm2) generates significant power dissipation under typical operating conditions. In this letter, we analyze the heating effect of these sandwich-type SNS junctions using a model to quantitatively estimate and predict thermal-transport properties of the stacked structures. We describe several strategies that reduce heating and demonstrate improved properties of stacked-junction arrays with enhanced cooling capacity.
Show PACS
74.45.+c Proximity effects; Andreev reflection; SN and SNS junctions
85.25.Cp Josephson devices
74.25.F- Transport properties
74.70.Ad Metals; alloys and binary compounds (including A15, MgB2, etc.)

X-ray photoemission electron microscopy investigation of magnetic thin film antidot arrays

L. J. Heyderman, F. Nolting, and C. Quitmann

Appl. Phys. Lett. 83, 1797 (2003); http://dx.doi.org/10.1063/1.1605804 (3 pages) | Cited 17 times

Online Publication Date: 26 August 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Periodic square arrays of antidots in 10 nm-thick cobalt films have been investigated with antidot periods, p, ranging from 2 μm down to 200 nm and various ratios of antidot size to antidot separation, w/d. For p = 2 μm, the extent of modification of the thin film magnetic domain structure increases with increasing w/d, forming domains pinned diagonally between antidots for w/d ≥ 0.2 and resulting in a two-dimensional periodic checked domain contrast commensurate with the antidot lattice for w/d ≥ 0.9. As p is decreased while maintaining d ≈ w, we observe a dramatic change in the magnetic domain configuration at p = 400 nm resulting in chains of magnetic domains running parallel to the intrinsic hard axis and with lengths corresponding to a multiple of the antidot period. © 2003 American Institute of Physics.
Show PACS
75.70.Kw Domain structure (including magnetic bubbles and vortices)
75.75.-c Magnetic properties of nanostructures
68.37.Xy Scanning Auger microscopy, photoelectron microscopy

Pinned synthetic ferrimagnets with perpendicular anisotropy and tuneable exchange bias

J. Sort, B. Rodmacq, S. Auffret, and B. Dieny

Appl. Phys. Lett. 83, 1800 (2003); http://dx.doi.org/10.1063/1.1606495 (3 pages) | Cited 22 times

Online Publication Date: 26 August 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Pinned synthetic ferrimagnets (syFerri) with perpendicular-to-plane magnetic anisotropy, of the form AP1/Ru/AP2/FeMn [where AP1 and AP2 are (Co/Pt) multilayers], have been prepared and characterized. The magnitudes of the exchange bias fields of both AP1 and AP2 can be tuned at room temperature by simply varying the relative number of (Co/Pt) repeats in each multilayer. This effect can be quantitatively interpreted by considering the different energy contributions involved during magnetization reversal. Moreover, from the values of these fields, the characteristic parameters of the system (i.e., coupling strength through the Ru and AP2/FeMn pinning energy), can be evaluated. Interestingly, an extended plateau with a virtually constant magnetization is observed around zero field when the number of Co/Pt repeats in AP1 is equal or larger than in AP2. This is very appealing for field sensor or memories applications using spin valves or tunnel junctions with perpendicular anisotropy, since it offers a large dynamic range over which the magnetic configuration of the syFerri remains stable. © 2003 American Institute of Physics.
Show PACS
75.70.Cn Magnetic properties of interfaces (multilayers, superlattices, heterostructures)
75.30.Et Exchange and superexchange interactions
75.30.Gw Magnetic anisotropy
75.60.Jk Magnetization reversal mechanisms
75.60.Ej Magnetization curves, hysteresis, Barkhausen and related effects
75.50.Ee Antiferromagnetics

Preparation of MgB2 tapes using a nanocrystalline partially reacted precursor

C. Fischer, C. Rodig, W. Häßler, O. Perner, J. Eckert, K. Nenkov, G. Fuchs, H. Wendrock, B. Holzapfel, and L. Schultz

Appl. Phys. Lett. 83, 1803 (2003); http://dx.doi.org/10.1063/1.1606498 (3 pages) | Cited 39 times

Online Publication Date: 26 August 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Fe-cladded MgB2 conductors have been prepared by the powder-in-tube method using mechanically alloyed nanocrystalline Mg+2B powder mixtures consisting of the constituents Mg, B, and MgB2 as precursor. Despite low Tc values of about 31 K, maximum critical current densities (Jc) of 22 and 7 kA/cm2 in external magnetic fields of 7.5 and 10 T, respectively, are achieved at 4.2 K. These excellent values can mainly be attributed to the very fine-grained microstructure of the superconducting phase. Higher values have only been reported for tapes doped with SiC nanoparticles. The irreversibility fields Hirr of these tapes are 9.5 and 4.2 T at 10 and 20 K, respectively. © 2003 American Institute of Physics.
Show PACS
74.70.Ad Metals; alloys and binary compounds (including A15, MgB2, etc.)
74.62.Bf Effects of material synthesis, crystal structure, and chemical composition
74.62.Dh Effects of crystal defects, doping and substitution
81.05.Je Ceramics and refractories (including borides, carbides, hydrides, nitrides, oxides, and silicides)
81.20.Ev Powder processing: powder metallurgy, compaction, sintering, mechanical alloying, and granulation
74.25.Sv Critical currents
74.25.Op Mixed states, critical fields, and surface sheaths
61.72.Cc Kinetics of defect formation and annealing
81.40.Gh Other heat and thermomechanical treatments

Antiferromagnetic interlayer exchange coupling across epitaxial, Ge-containing spacers

R. R. Gareev, D. E. Bürgler, R. Schreiber, H. Braak, M. Buchmeier, and P. A. Grünberg

Appl. Phys. Lett. 83, 1806 (2003); http://dx.doi.org/10.1063/1.1606102 (3 pages) | Cited 3 times

Online Publication Date: 26 August 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We give experimental evidence of antiferromagnetic interlayer exchange coupling of Fe(001) layers across epitaxial, Ge-containing spacers consisting of either Ge wedges embedded between two Si boundary layers or Si–Ge-multilayers. The coupling strengths are of the order of 1 mJ/m2 and decay on a length scale below 2 Å as determined from magneto-optic Kerr effect and Brillouin light scattering. The coupling evolves with the spacer thickness from ferromagnetic to prevailing 90° or antiferromagnetic for Ge wedges and Si–Ge multilayers, respectively. The bilinear coupling is comparable in both cases, but the biquadratic contribution is suppressed for Si–Ge-multilayer spacers. Thus, Si–Ge-multilayer spacers give rise to perfect antiparallel alignment of the Fe film magnetizations. © 2003 American Institute of Physics.
Show PACS
75.70.Cn Magnetic properties of interfaces (multilayers, superlattices, heterostructures)
75.30.Et Exchange and superexchange interactions
78.20.Ls Magneto-optical effects
75.60.Ej Magnetization curves, hysteresis, Barkhausen and related effects
78.35.+c Brillouin and Rayleigh scattering; other light scattering

Observation of MnP magnetic clusters in room-temperature ferromagnetic semiconductor Zn1−xMnxGeP2 using nuclear magnetic resonance

Taesoon Hwang, Jeong Hyun Shim, and Soonchil Lee

Appl. Phys. Lett. 83, 1809 (2003); http://dx.doi.org/10.1063/1.1605260 (3 pages) | Cited 9 times

Online Publication Date: 26 August 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We investigated chalcopyrite Zn1−xMnxGeP2 polycrystals, which have been reported as a room-temperature ferromagnetic semiconductor, with Mn concentrations of x = 0.08 and 0.15 using 55Mn and 31P nuclear magnetic resonance spectroscopy. The samples were made by the same process and showed the same crystallographic and magnetic behavior as in the previous report, but the experimental results indicated that more than 90% of Mn atoms were in a MnP impurity phase and the MnP cluster size was tens of nanometers. No evidence of Mn atom substitution in the host ZnGeP2 lattice was observed and the magnetic property of Zn1−xMnxGeP2 was determined to be that of the MnP magnetic clusters, at least in the bulk. The inconsistency of the conclusions with x-ray diffraction data is a result of the weak crystallinity of MnP phase. © 2003 American Institute of Physics.
Show PACS
76.60.-k Nuclear magnetic resonance and relaxation
75.50.Dd Nonmetallic ferromagnetic materials
75.50.Pp Magnetic semiconductors
61.66.Fn Inorganic compounds

Spin polarization and magnetotransport of Mn–Sb alloys in magnetic tunnel junctions

Alex F. Panchula, Christian Kaiser, Andrew Kellock, and Stuart S. P. Parkin

Appl. Phys. Lett. 83, 1812 (2003); http://dx.doi.org/10.1063/1.1606108 (3 pages) | Cited 5 times

Online Publication Date: 26 August 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The spin polarization of MnxSb1−x for x = 0.35–0.45 has been explored via magnetic tunnel junctions using CoFe counterelectrodes and via superconducting tunneling spectroscopy using Al counterelectrodes. MnxSb1−x with x ∼ 0.45 shows a tunneling spin polarization of ∼30% at 0.25 K, and a tunneling magnetoresistance of ∼18% at 10 K both of which are very similar to previously reported data on NiMnSb alloys. These results support the notion that surface segregation of Mn and Sb reduces the spin polarization of the purported half-metal NiMnSb. © 2003 American Institute of Physics.
Show PACS
72.25.Mk Spin transport through interfaces
85.75.Mm Spin polarized resonant tunnel junctions
75.47.Np Metals and alloys
68.35.Dv Composition, segregation; defects and impurities
74.50.+r Tunneling phenomena; Josephson effects
Return to All Sections
Close

Google Calendar

ADVERTISEMENT

Go to AIP Home   © AIP Publishing LLC
close