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

30 Apr 2001

Volume 78, Issue 18, pp. 2617-2804

Return to All Sections
back to top
RSS Feeds

Coexistence of intrinsic and extrinsic magnetoresistance in the double-perovskite Sr2Fe(Mo1−xWx)O6−w system

J. Lindén, T. Yamamoto, J. Nakamura, M. Karppinen, and H. Yamauchi

Appl. Phys. Lett. 78, 2736 (2001); http://dx.doi.org/10.1063/1.1366357 (3 pages) | Cited 6 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
In a recent study, it was shown that by partially substituting Mo with W in the double-perovskite Sr2FeMoO6−w system, the magnetoresistivity can be enhanced. [K.-I. Kobayashi, T. Okuda, Y. Tomioka, T. Kimura, and Y. Tokura, J. Magn. Magn. Mater. 218, 17 (2000).] In order to explain the increase in the magnetoresistivity a series of W-substituted Sr2Fe(Mo1−xWx)O6−w samples with 0 ⩽ x ⩽ 1 was synthesized. Upon increasing the W content, the samples began to exhibit coexistence of paramagnetism and ferrimagnetism at 300 K. Signatures of antiferromagnetic ordering appeared around TN ≈ 50 K for x ≥ 0.6. In samples with 0.7 ⩽ x ⩽ 0.8 a broad peak was observed in the magnetoresistance data at temperatures corresponding to the Néel temperature. The peak was found to have its origin in the colossal magnetoresistance effect. The W-substituted samples were partially ferrimagnetic and therefore also exhibited the tunneling-type magnetoresistance, which is characteristic of pure Sr2FeMoO6−w. The coexistence of the two types of magnetoresistance effect is responsible for the enhancement of the overall magnetoresistance value. A slight enhancement in the magnetoresistance values around 300 K for the strongly W-substituted samples was found to be related to a second colossal magnetoresistance peak related to the para- to ferrimagnetic transition at Tc. © 2001 American Institute of Physics.
Show PACS
75.47.Gk Colossal magnetoresistance
75.30.Kz Magnetic phase boundaries (including classical and quantum magnetic transitions, metamagnetism, etc.)
75.20.Ck Nonmetals
75.50.Gg Ferrimagnetics
75.50.Ee Antiferromagnetics

Magnetoresistance of Mn:Ge ferromagnetic nanoclusters in a diluted magnetic semiconductor matrix

Y. D. Park, A. Wilson, A. T. Hanbicki, J. E. Mattson, T. Ambrose, G. Spanos, and B. T. Jonker 

Appl. Phys. Lett. 78, 2739 (2001); http://dx.doi.org/10.1063/1.1369151 (3 pages) | Cited 89 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We have fabricated a thin film magnetic system consisting of nanoscale Mn11Ge8 ferromagnetic clusters embedded in a MnxGe1−x dilute ferromagnetic semiconductor matrix. The clusters form for growth temperatures of ∼300 °C with an average diameter and spacing of 100 and 150 nm, respectively. While the clusters dominate the magnetic properties, the matrix plays a subtle but interesting role in determining the transport properties. Variable range hopping at low temperatures involves both nanoclusters and MnGe sites, and is accompanied by a negative magnetoresistance attributed in part to spin-dependent scattering analogous to metallic granular systems. © 2001 American Institute of Physics.
Show PACS
73.50.Jt Galvanomagnetic and other magnetotransport effects (including thermomagnetic effects)
72.15.Gd Galvanomagnetic and other magnetotransport effects
72.20.My Galvanomagnetic and other magnetotransport effects
61.46.-w Structure of nanoscale materials
73.63.Bd Nanocrystalline materials
75.50.Tt Fine-particle systems; nanocrystalline materials
81.07.Bc Nanocrystalline materials
75.50.Dd Nonmetallic ferromagnetic materials
75.50.Pp Magnetic semiconductors
75.70.Ak Magnetic properties of monolayers and thin films
72.20.Ee Mobility edges; hopping transport
73.61.Le Other inorganic semiconductors

Vector magnetization imaging in ferromagnetic thin films using soft x-rays

Sang-Koog Kim, J. B. Kortright, and Sung-Chul Shin

Appl. Phys. Lett. 78, 2742 (2001); http://dx.doi.org/10.1063/1.1370120 (3 pages) | Cited 15 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
A magnetization vector M imaging using a transmission x-ray microscope with magnetic circular dichroism (MCD) contrast is demonstrated. MCD images through a semitransparent, 33-nm-thick Fe film are measured at the Fe L3 edge along three different x-ray propagation directions to determine all three components of the M. The transmission images clearly display the vector nature of complex microstructures, associated with the M reversal between oppositely oriented 180° domains, including not only 90° domains, a Néel wall-like structure, and an extended ripple structure, but also a striking feature of localized magnetization spirals with perpendicular components at their cores. These studies have important implications for applications of this technique to better understand the expected features as well as details of domain-wall structures. © 2001 American Institute of Physics.
Show PACS
75.50.Bb Fe and its alloys
75.70.-i Magnetic properties of thin films, surfaces, and interfaces
75.60.Ej Magnetization curves, hysteresis, Barkhausen and related effects
78.70.Dm X-ray absorption spectra
75.60.Ch Domain walls and domain structure
75.70.Kw Domain structure (including magnetic bubbles and vortices)

Axial high-temperature superconducting-quantum-interference-device gradiometer composed of magnetometers with a monolithic feedback and compensation coil

Koichi Yokosawa, Hiroshi Oyama, Shinya Kuriki, Daisuke Suzuki, and Keiji Tsukada

Appl. Phys. Lett. 78, 2745 (2001); http://dx.doi.org/10.1063/1.1369414 (3 pages) | Cited 4 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
A first-order axial gradiometer has been constructed using two high-critical-temperature superconducting-quantum-interference-device magnetometers having a double-pickup loop configuration on bicrystal substrates. The magnetometer, which had a slot-type structure but no weak links on the pickup loops, can be operated steadily in an unshielded environment after in situ cooling. The gradiometer was formed by connecting the feedback and the compensation coils of the two magnetometers in series using a normal conductive wire. Sufficiently high noise reduction (31 dB at 1 Hz) was achieved without any need for adjustments and low-noise magnetocardiograms were obtained with the gradiometer in a moderately magnetically shielded room. © 2001 American Institute of Physics.
Show PACS
07.55.Ge Magnetometers for magnetic field measurements
85.25.Dq Superconducting quantum interference devices (SQUIDs)
87.19.Hh Cardiac dynamics
87.50.C- Static and low-frequency electric and magnetic fields effects
07.55.Nk Magnetic shielding in instruments

Dynamic coercivity measurements of antiferromagnetically coupled magnetic media layers

J. Lohau, A. Moser, D. T. Margulies, E. E. Fullerton, and M. E. Schabes

Appl. Phys. Lett. 78, 2748 (2001); http://dx.doi.org/10.1063/1.1369391 (3 pages) | Cited 22 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We have performed dynamic coercivity measurements on a series of antiferromagnetically coupled (AFC) magnetic recording media utilizing a static write/read tester. The samples consist of two magnetic layers, which are antiferromagnetically coupled by a nonmagnetic layer. The investigated samples have a fixed top layer thickness and variable bottom layer thickness, such that the composite remanent magnetization thickness product (MRtAFC) varies over a large range, 0.17–0.30 memu/cm2. We find that the ratio between anisotropy energy and thermal energy (≡ stability ratio, C−1), and the intrinsic switching field H0 are, within the experimental error, constant for the series. This suggests that the top magnetic layer to first order determines the stability ratio of the AFC media and that MRtAFC can be varied over a large range without decreasing the stability or increasing the write field requirements. © 2001 American Institute of Physics.
Show PACS
75.50.Ss Magnetic recording materials
75.70.Ak Magnetic properties of monolayers and thin films
75.50.Vv High coercivity materials
75.60.Ej Magnetization curves, hysteresis, Barkhausen and related effects
Return to All Sections
Close

Google Calendar

ADVERTISEMENT

Go to AIP Home   © AIP Publishing LLC
close