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

29 Apr 2002

Volume 80, Issue 17, pp. 3033-3231

Return to All Sections
back to top
RSS Feeds

60% magnetoresistance at room temperature in Co–Fe/Al–O/Co–Fe tunnel junctions oxidized with Kr–O2 plasma

Masakiyo Tsunoda, Kazuhiro Nishikawa, Satoshi Ogata, and Migaku Takahashi

Appl. Phys. Lett. 80, 3135 (2002); http://dx.doi.org/10.1063/1.1475363 (3 pages) | Cited 41 times

Online Publication Date: 22 April 2002

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The influence of the mixed inert gas species for plasma oxidization process of a metallic Al layer on the tunnel magnetoresistance (TMR) was investigated for a magnetic tunnel junction (MTJ), Ta 50 Å/Cu 200 Å/Ta 200 Å/Ni–Fe 50 Å/Cu 50 Å/Mn75Ir25 100 Å/Co70Fe30 25 Å/Al–O/Co70Fe30 25 Å/Ni–Fe 100 Å/Cu 200 Å/Ta 50 Å. Using Kr–O2 plasma, a 58.8% of TMR ratio was obtained at room temperature after annealing the junction at 300 °C, while the achieved TMR ratio of the MTJ fabricated with usual Ar–O2 plasma remained 48.6%. A faster oxidization rate of the Al layer by using Kr–O2 plasma is a possible cause to prevent the over oxidization of the Al layer, which depolarizes the surface of the underlaid ferromagnetic electrode, and to realize a large magnetoresistance. © 2002 American Institute of Physics.
Show PACS
75.70.Cn Magnetic properties of interfaces (multilayers, superlattices, heterostructures)
75.47.De Giant magnetoresistance
73.61.At Metal and metallic alloys
81.05.Bx Metals, semimetals, and alloys
73.50.Jt Galvanomagnetic and other magnetotransport effects (including thermomagnetic effects)
73.40.Rw Metal-insulator-metal structures
61.72.Cc Kinetics of defect formation and annealing
52.77.-j Plasma applications
81.65.Mq Oxidation

Anomalous Hall effect in La1−xCaxCoO3

S. A. Baily, M. B. Salamon, Y. Kobayashi, and K. Asai

Appl. Phys. Lett. 80, 3138 (2002); http://dx.doi.org/10.1063/1.1473866 (3 pages) | Cited 13 times

Online Publication Date: 22 April 2002

Full Text: Read Online (HTML) | Download PDF

Show Abstract
La1−xCaxCoO3 films show the largest anomalous Hall effect of any ferromagnetic metal. The anomalous Hall coefficient increases as x decreases. At doping below 0.2 La1−xCaxCoO3 is insulating and shows spin-glass behavior at low temperature. We have measured the Hall effect and magnetic behavior of an x = 0.15 crystal. It shows cluster-glass or correlated-spin-glass behavior at intermediate temperatures. The anomalous Hall effect does not depend on the total magnetization, M, but on the ferromagnetic correlations of the glass. © 2002 American Institute of Physics.
Show PACS
72.20.My Galvanomagnetic and other magnetotransport effects
75.50.Dd Nonmetallic ferromagnetic materials
75.50.Lk Spin glasses and other random magnets
75.60.Ej Magnetization curves, hysteresis, Barkhausen and related effects

Local magnetic ordering in La1−xCaxMnO3 determined by spin-polarized x-ray absorption spectroscopy

Q. Qian, T. A. Tyson, C.-C. Kao, M. Croft, and A. Yu. Ignatov

Appl. Phys. Lett. 80, 3141 (2002); http://dx.doi.org/10.1063/1.1473700 (3 pages) | Cited 8 times

Online Publication Date: 22 April 2002

Full Text: Read Online (HTML) | Download PDF

Show Abstract
A systematic study of spin-dependent Mn K-edge x-ray absorption spectra was performed on La1−xCaxMnO3. By examining the changes in the pre-edge spectra with the temperature, a model of the excitation process is developed and used to predict the temperature dependent changes in the local magnetic ordering about Mn sites. The approach is of general applicability to perovskite systems. It can be used to determine the change in the local magnetic order (ferromagnetic versus antiferromagnetic) about a transition metal site upon going through a transition or as the result of external perturbations. © 2002 American Institute of Physics.
Show PACS
75.30.Kz Magnetic phase boundaries (including classical and quantum magnetic transitions, metamagnetism, etc.)
75.47.Gk Colossal magnetoresistance
78.70.Dm X-ray absorption spectra

Spin-coherent transport in ferromagnetically contacted carbon nanotubes

B. Zhao, I. Mönch, H. Vinzelberg, T. Mühl, and C. M. Schneider

Appl. Phys. Lett. 80, 3144 (2002); http://dx.doi.org/10.1063/1.1471570 (3 pages) | Cited 71 times

Online Publication Date: 22 April 2002

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The spin-coherent quantum transport through multiwall carbon nanotubes contacted by ferromagnetic Co pads is investigated experimentally. At 4.2 K, the devices show a remarkable increase of the magnetoresistance (MR) ratio with decreasing junction bias, reaching a maximum MR ratio of 30% at a junction bias current of 1 nA. The experimental results suggest the transport to be dominated by spin-dependent tunneling processes at the Co/nanotube interfaces and governed by the local magnetization. We also observe an asymmetry of the magnetoresistance peak position and width which is attributed to a local exchange biasing in the electrode material. © 2002 American Institute of Physics.
Show PACS
72.25.Mk Spin transport through interfaces
73.63.Fg Nanotubes
75.50.Cc Other ferromagnetic metals and alloys
75.45.+j Macroscopic quantum phenomena in magnetic systems

Resonant terahertz radiation from Tl2Ba2CaCu2O8+δ thin films by ultrafast optical pulse excitation

Yukihiro Tominari, Toshihiko Kiwa, Hironaru Murakami, Masayoshi Tonouchi, Hagen Wald, Paul Seidel, and Henrik Schneidewind

Appl. Phys. Lett. 80, 3147 (2002); http://dx.doi.org/10.1063/1.1475770 (3 pages) | Cited 16 times

Online Publication Date: 22 April 2002

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We have observed the free-space radiation of the resonant terahertz wave from c-axis oriented Tl2Ba2CaCu2O8+δ thin films by femtosecond optical pulse excitation under a radial magnetic field of about 100 Oe nearly parallel to the c axis of the thin film. The observed wave form showed clear oscillations up to 80 K. The frequency was shifted from ∼ 620 GHz at 24 K to ∼ 300 GHz at 80 K, corresponding to an increase in c-axis penetration depth, λc, from ∼ 26 μm to ∼ 53 μm, and disappeared above TC as expected for the Josephson plasma resonance. © 2002 American Institute of Physics.
Show PACS
74.72.-h Cuprate superconductors
74.78.-w Superconducting films and low-dimensional structures
74.25.N- Response to electromagnetic fields
74.50.+r Tunneling phenomena; Josephson effects
74.25.Ha Magnetic properties including vortex structures and related phenomena

Stroboscopic single-shot detection of the flux state in a radio frequency superconducting quantum interference device

C. Cosmelli, F. Sciamanna, M. G. Castellano, R. Leoni, G. Torrioli, P. Carelli, and F. Chiarello

Appl. Phys. Lett. 80, 3150 (2002); http://dx.doi.org/10.1063/1.1474605 (3 pages) | Cited 10 times

Online Publication Date: 22 April 2002

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The flux states of a rf superconducting quantum interference device (SQUID) can be used to investigate macroscopic quantum effects, the most challenging of which is the detection of quantum coherent oscillations, and are promising candidates for the implementation of quantum computing. The use of a proper readout system is of utmost importance for these purposes. In this letter we present experimental evidence of the possibility of using an underdamped, hysteretic dc SQUID to read out stroboscopically the flux states of a rf SQUID, allowing a single shot discrimination with an efficiency of 98%. The devices are all integrated on chip. © 2002 American Institute of Physics.
Show PACS
85.25.Dq Superconducting quantum interference devices (SQUIDs)
03.67.Lx Quantum computation architectures and implementations

Fluxon insertion into annular Josephson junctions

Alexey V. Ustinov

Appl. Phys. Lett. 80, 3153 (2002); http://dx.doi.org/10.1063/1.1474617 (3 pages) | Cited 30 times

Online Publication Date: 22 April 2002

Full Text: Read Online (HTML) | Download PDF

Show Abstract
A technique of inserting magnetic fluxons into annular Josephson junctions is proposed and demonstrated experimentally. The method is based on local injection of current into one of the superconducting electrodes of the junction. The residual pinning of fluxons in the junction can be eliminated by choosing an appropriate injection current, which depends on the spacing between the injectors. The reported technique resolves the long-standing problem of a controlled preparation of fluxon states in annular Josephson junctions and can be used in various fluxon devices. © 2002 American Institute of Physics.
Show PACS
85.25.Cp Josephson devices
74.50.+r Tunneling phenomena; Josephson effects
74.25.Uv Vortex phases (includes vortex lattices, vortex liquids, and vortex glasses)
74.45.+c Proximity effects; Andreev reflection; SN and SNS junctions

Spin valves with interlayer coupling domain biasing

Z. Q. Lu and G. Pan

Appl. Phys. Lett. 80, 3156 (2002); http://dx.doi.org/10.1063/1.1471930 (3 pages) | Cited 4 times

Online Publication Date: 22 April 2002

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Spin valves with structure of sub/Ta/NiFe/FeMn/NiFe/Mo/NiFe/Cu/NiFe/CrMnPt/Ta were developed. In this configuration, a longitudinal-biasing field from interlayer coupling stabilized the magnetic domains of the free layer. Planar Hall effect was used to study the magnetization reversal process of the free layer. It was shown that by adjusting the thickness of Mo layer, the interlayer coupling biasing field can provide domain stabilization and was sufficiently strong to constrain the magnetization in coherent rotation. This can prevent Barkhausen noises associated with magnetization reversal. Such a spin valve sensor structure is particularly attractive for high density read heads. © 2002 American Institute of Physics.
Show PACS
75.47.De Giant magnetoresistance
75.70.Kw Domain structure (including magnetic bubbles and vortices)
75.60.Jk Magnetization reversal mechanisms
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.
Return to All Sections
Close

Google Calendar

ADVERTISEMENT

Go to AIP Home   © AIP Publishing LLC
close