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

15 Jul 2002

Volume 81, Issue 3, pp. 391-566

Return to All Sections
back to top
RSS Feeds

Accurate oxygen-content determination method for decreased sample amounts of superconductive and other functional oxides

Yukiko Yasukawa, Hisao Yamauchi, and Maarit Karppinen

Appl. Phys. Lett. 81, 502 (2002); http://dx.doi.org/10.1063/1.1490146 (3 pages) | Cited 3 times

Online Publication Date: 2 July 2002

Full Text: Read Online (HTML) | Download PDF

Show Abstract
In a conventional wet-chemical redox analysis applied to the determination of oxygen contents of nonstoichiometric functional oxides such as superconductive copper oxides, the sample amount required for a single experiment is typically 50–100 mg. Here we demonstrate that an improved coulometric titration method works to precisely analyze oxygen contents of decreased amounts of various complex oxides containing, e.g., copper, cobalt, or iron at mixed valence values. The improved titration method is found to yield the oxygen content of the YBa2Cu3O7−δ reference sample with high reproducibility, i.e., ∣Δδ∣<0.01, for samples with a mass of only ∼ 10 mg. © 2002 American Institute of Physics.
Show PACS
82.80.-d Chemical analysis and related physical methods of analysis
74.72.-h Cuprate superconductors

Probing microwave properties of high-Tc films via small dc magnetic fields

Peter Lahl and Roger Wördenweber

Appl. Phys. Lett. 81, 505 (2002); http://dx.doi.org/10.1063/1.1487902 (3 pages) | Cited 11 times

Online Publication Date: 2 July 2002

Full Text: Read Online (HTML) | Download PDF

Show Abstract
It is demonstrated that the combination of vortex matter and rf measurements yields new insight into the microwave properties of superconducting thin-film devices, both in small magnetic fields and zero field. The comparison of field-cooled and different types of field-sweep experiments on coplanar high-Tc thin-film resonators shows that the microwave properties strongly depend on magnetization and vortex distribution in the superconducting film as well. Thus, using vortices as a kind of local probe for the microwave properties leads to a consistent explanation of the microwave power handling in nonzero and zero magnetic fields. In a model that is derived from the experiments, the nonlinear microwave behavior is explained by the limitation of the total current density in the device considering contributions of the rf field and the screening of the magnetic field and vortices to the current. The limiting current value seems to be related to the dc critical current of the superconductor. © 2002 American Institute of Physics.
Show PACS
74.78.-w Superconducting films and low-dimensional structures
74.25.N- Response to electromagnetic fields
74.72.-h Cuprate superconductors
74.25.Uv Vortex phases (includes vortex lattices, vortex liquids, and vortex glasses)
74.25.Sv Critical currents
85.25.-j Superconducting devices
84.40.Az Waveguides, transmission lines, striplines

State switching in Bi-doped La0.67Ca0.33MnO3 and the effects of current

J. R. Sun, J. Gao, and L. Kang

Appl. Phys. Lett. 81, 508 (2002); http://dx.doi.org/10.1063/1.1494109 (3 pages) | Cited 4 times

Online Publication Date: 2 July 2002

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Electronic transport and magnetic properties of La0.477Bi0.193Ca0.33MnO3 have been experimentally studied. Different resistive behaviors are observed in the cooling and warming processes. The system first stays at a high resistive state, and switches to a state of lower resistivity when it is cooled below a critical temperature. However, keeping the sample at a temperature below ∼60 K, a relaxation to the high resistive state takes place. This process is current dependent, and the application of a large current slows down the relaxation greatly. There is a strong competition between the two resistive states, which causes a switch of the system between states. © 2002 American Institute of Physics.
Show PACS
72.60.+g Mixed conductivity and conductivity transitions
81.40.Gh Other heat and thermomechanical treatments
81.40.Rs Electrical and magnetic properties related to treatment conditions
72.20.Fr Low-field transport and mobility; piezoresistance

Above-room-temperature ferromagnetism in GaSb/Mn digital alloys

X. Chen, M. Na, M. Cheon, S. Wang, H. Luo, B. D. McCombe, X. Liu, Y. Sasaki, T. Wojtowicz, J. K. Furdyna, S. J. Potashnik, and P. Schiffer

Appl. Phys. Lett. 81, 511 (2002); http://dx.doi.org/10.1063/1.1481184 (3 pages) | Cited 65 times

Online Publication Date: 2 July 2002

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Digital alloys of GaSb/Mn have been fabricated by molecular-beam epitaxy. Transmission electron micrographs showed good crystal quality with individual Mn-containing layers well resolved, no evidence of three-dimensional MnSb precipitates was seen in as-grown samples. All samples studied exhibited ferromagnetism with temperature-dependent hysteresis loops in the magnetization accompanied by metallic p-type conductivity with a strong anomalous Hall effect (AHE) up to 400 K (limited by the experimental setup). The anomalous Hall effect shows hysteresis loops at low temperatures and above room temperature very similar to those seen in the magnetization. The strong AHE with hysteresis indicates that the holes interact with the Mn spins above room temperature. All samples are metallic, which is important for spintronics applications. © 2002 American Institute of Physics.
Show PACS
75.50.Pp Magnetic semiconductors
75.70.Ak Magnetic properties of monolayers and thin films
73.50.Jt Galvanomagnetic and other magnetotransport effects (including thermomagnetic effects)
72.25.Dc Spin polarized transport in semiconductors
75.60.Ej Magnetization curves, hysteresis, Barkhausen and related effects
75.50.Dd Nonmetallic ferromagnetic materials
68.37.Lp Transmission electron microscopy (TEM)
72.15.Gd Galvanomagnetic and other magnetotransport effects
72.20.My Galvanomagnetic and other magnetotransport effects
75.47.De Giant magnetoresistance
73.61.Ey III-V semiconductors

Tunneling magnetoresistance of Co clusters in MgF2

B. Hackenbroich, H. Zare-Kolsaraki, and H. Micklitz

Appl. Phys. Lett. 81, 514 (2002); http://dx.doi.org/10.1063/1.1494467 (3 pages) | Cited 11 times

Online Publication Date: 2 July 2002

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Samples of Co clusters embedded in a MgF2 matrix have been prepared by the codeposition of well-defined Co clusters (mean diameter L ≃ 4.5 nm) and MgF2 molecules onto a cold substrate. This system shows a temperature-dependent tunneling magnetoresistance (TMR) which has a value of 34.7(2)% at 2.5 K, the largest TMR value reported for a granular Co system. This large TMR value either is due to an antiferromagnetic coupling of those Co clusters between which the tunneling occurs or is caused by an enhanced spin-polarization of the tunneling electrons. The latter may be caused by a cluster–surface/matrix interaction leading to dominated d-electron tunneling due to Co(3d)–F(2p) hybridization. © 2002 American Institute of Physics.
Show PACS
75.50.Tt Fine-particle systems; nanocrystalline materials
75.50.Ee Antiferromagnetics
75.30.Et Exchange and superexchange interactions
75.47.De Giant magnetoresistance

Miscut-angle dependence of perpendicular magnetic anisotropy in thin epitaxial CoPt3 films grown on vicinal MgO

B. B. Maranville, A. L. Shapiro, F. Hellman, D. M. Schaadt, and E. T. Yu

Appl. Phys. Lett. 81, 517 (2002); http://dx.doi.org/10.1063/1.1491610 (3 pages) | Cited 10 times

Online Publication Date: 2 July 2002

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The effect of vicinal substrates on the growth-induced perpendicular magnetic anisotropy of epitaxial CoPt3 films has been studied. A small (2°, 4°, or 10°) miscut angle of the vicinal substrate causes the crystallographic axes of the sample to be tilted along the miscut direction. The magnitude of the perpendicular anisotropy is unaffected by the presence of substrate steps produced by the miscut angle, while an additional, in-plane anisotropy develops with a larger miscut angle. Effects of the steps are seen in magnetic force microscopic images of domain wall pinning. © 2002 American Institute of Physics.
Show PACS
75.70.Ak Magnetic properties of monolayers and thin films
75.30.Gw Magnetic anisotropy
81.05.Bx Metals, semimetals, and alloys
68.55.-a Thin film structure and morphology
68.35.B- Structure of clean surfaces (and surface reconstruction)
68.37.Rt Magnetic force microscopy (MFM)
75.70.Kw Domain structure (including magnetic bubbles and vortices)

Cobalt–oxide underlayers for cobalt–ferrite pinned spin valves

S. Maat, M. J. Carey, Eric E. Fullerton, T. X. Le, P. M. Rice, and B. A. Gurney

Appl. Phys. Lett. 81, 520 (2002); http://dx.doi.org/10.1063/1.1494461 (3 pages) | Cited 14 times

Online Publication Date: 2 July 2002

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We report on the advantages of employing insulating Co–oxide underlayers for spin valves utilizing Co–ferrite as a pinning layer. These underlayers provide for improved crystalline growth of Co-ferrite pinning layers, which can be reduced to as little as 3 nm in thickness while maintaining high coercivity and thermal stability. This allows a typical antiferromagnetically pinned spin valve to fit into a 50 nm gap, which is anticipated for recording densities >100 Gbit/in2. Magnetoresistance values ∼7%, excellent stability, and free layer properties are observed and pinned which is comparable to present PtMn based sensors of similar thickness. © 2002 American Institute of Physics.
Show PACS
75.70.Cn Magnetic properties of interfaces (multilayers, superlattices, heterostructures)
75.50.Gg Ferrimagnetics
75.47.De Giant magnetoresistance
75.60.Ej Magnetization curves, hysteresis, Barkhausen and related effects
85.70.Kh Magnetic thin film devices: magnetic heads (magnetoresistive, inductive, etc.); domain-motion devices, etc.
68.60.Dv Thermal stability; thermal effects
Return to All Sections
Close

Google Calendar

ADVERTISEMENT

Go to AIP Home   © AIP Publishing LLC
close