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

19 Apr 2004

Volume 84, Issue 16, pp. 2971-3207

Issue Cover Spotlight Figure

Appl. Phys. Lett. 84, 3139 (2004); http://dx.doi.org/10.1063/1.1710717 (3 pages)

Slava V. Rotkin and Karl Hess
Enlarge Image | Read More
Return to All Sections
back to top
RSS Feeds

Exploration of artificial multiferroic thin-film heterostructures using composition spreads

K.-S. Chang, M. A. Aronova, C.-L. Lin, M. Murakami, M.-H. Yu, J. Hattrick-Simpers, O. O. Famodu, S. Y. Lee, R. Ramesh, M. Wuttig, I. Takeuchi, C. Gao, and L. A. Bendersky

Appl. Phys. Lett. 84, 3091 (2004); http://dx.doi.org/10.1063/1.1699474 (3 pages) | Cited 42 times

Online Publication Date: 13 April 2004

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We have fabricated a series of composition spreads consisting of ferroelectric BaTiO3 and piezomagnetic CoFe2O4 layers of varying thicknesses modulated at nanometer level in order to explore artificial magnetoelectric thin-film heterostructures. Scanning microwave microscopy and scanning superconducting quantum interference device microscopy were used to map the dielectric and magnetic properties as a function of continuously changing average composition across the spreads, respectively. Compositions in the middle of the spreads were found to exhibit ferromagnetism while displaying a dielectric constant as high as ≈ 120. © 2004 American Institute of Physics.
Show PACS
77.84.Ek Niobates and tantalates
77.84.Cg PZT ceramics and other titanates
75.50.Tt Fine-particle systems; nanocrystalline materials
77.55.-g Dielectric thin films
75.80.+q Magnetomechanical effects, magnetostriction
75.50.Dd Nonmetallic ferromagnetic materials
75.70.Ak Magnetic properties of monolayers and thin films
75.70.Cn Magnetic properties of interfaces (multilayers, superlattices, heterostructures)
77.22.Ch Permittivity (dielectric function)
75.60.Ej Magnetization curves, hysteresis, Barkhausen and related effects

Crystal structure and magnetic properties of SmCo5.85Si0.90 compound

J. Luo, J. K. Liang, Y. Q. Guo, Q. L. Liu, L. T. Yang, F. S. Liu, and G. H. Rao

Appl. Phys. Lett. 84, 3094 (2004); http://dx.doi.org/10.1063/1.1712026 (3 pages) | Cited 32 times

Online Publication Date: 13 April 2004

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The crystal structure and magnetic properties of SmCo7−xSix (x = 0.1–0.9) compounds were studied by means of x-ray powder diffraction and magnetic measurements. Rietveld refinement of x-ray powder diffraction pattern shows that the as-cast compound SmCo7−xSix with x = 0.9 crystallizes in the TbCu7-type structure with the space group P6/mmm, and the doping element Si has a distinct preference to occupy the 3g site. According to the refinement result, the composition of the compound is derived as SmCo5.85Si0.90. The compound SmCo5.85Si0.90 exhibits ferromagnetic order with the Curie temperature of about 717 K and a saturation moment of about 6.58±0.05 μB/f.u. The SmCo5.85Si0.90 compound shows a strong uniaxial magnetocrystalline anisotropy, and an anomalous increase of magnetization at low temperature is observed in an external field applied perpendicular to the easy direction of magnetization. © 2004 American Institute of Physics.
Show PACS
75.30.Kz Magnetic phase boundaries (including classical and quantum magnetic transitions, metamagnetism, etc.)
75.60.Ej Magnetization curves, hysteresis, Barkhausen and related effects
75.50.Cc Other ferromagnetic metals and alloys
61.66.Dk Alloys
75.30.Cr Saturation moments and magnetic susceptibilities
75.30.Gw Magnetic anisotropy
64.70.K- Solid-solid transitions

Giant magnetoresistance in PtMn alloys

M. J. Carey, A. B. Banful, L. Folks, B. A. Gurney, R. F. C. Farrow, and A. J. Kellock

Appl. Phys. Lett. 84, 3097 (2004); http://dx.doi.org/10.1063/1.1712022 (3 pages) | Cited 6 times

Online Publication Date: 13 April 2004

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The onset of chemical and magnetic order in PtMn is accompanied by a large increase in the resistivity, ρ, contrary to that observed in nonmagnetic or ferromagnetic disorder–order transitions. We attribute this to a giant magnetoresistance like magnetic scattering off the antiferromagnetically aligned spins within the PtMn. The characteristics of the resistance change with anneal time in two regimes, with only the second regime involving a disorder/order transition. We have used the change of ρ with time to calculate the activation energy for the L10 transformation in PtMn and found it to be about 1.5 eV for thick films. The activation energy increases significantly for thinner films. © 2004 American Institute of Physics.
Show PACS
75.50.Ee Antiferromagnetics
72.15.Gd Galvanomagnetic and other magnetotransport effects
81.30.Hd Constant-composition solid-solid phase transformations: polymorphic, massive, and order-disorder
75.47.De Giant magnetoresistance
81.40.Gh Other heat and thermomechanical treatments
75.30.Kz Magnetic phase boundaries (including classical and quantum magnetic transitions, metamagnetism, etc.)

Transition of magnetic state from A-type antiferromagnetic to ferromagnetic in electron-doped Nd1−xCexMnO3

Shixiong Zhang, Lan Luan, Shun Tan, and Yuheng Zhang

Appl. Phys. Lett. 84, 3100 (2004); http://dx.doi.org/10.1063/1.1712023 (3 pages) | Cited 6 times

Online Publication Date: 13 April 2004

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The transition of the magnetic state with x increasing in electron-doped manganite Nd1−xCexMnO3 is investigated through the measurements of magnetism, including the M–T and hysteresis curves. For x = 0.04, with temperature increasing, M under zero-field cooling indicates that the magnetic structure changes from ferromagnetic (FM) to antiferromagnetic then to FM again and finally turns to paramagnetic (PM). However, the field-cooling M–T curve shows a negative M at 5 K then increases rapidly to a positive maximum and finally turns to PM. The experiment results are well fitted with Weiss’s molecular field theory and Néel’s ferrimagnetic model. With the enhancement of Ce content (x = 0.08 and 0.10), this system gradually exhibits simple transition from FM to PM. © 2004 American Institute of Physics.
Show PACS
75.50.Ee Antiferromagnetics
75.30.Kz Magnetic phase boundaries (including classical and quantum magnetic transitions, metamagnetism, etc.)
75.60.Ej Magnetization curves, hysteresis, Barkhausen and related effects
75.25.-j Spin arrangements in magnetically ordered materials (including neutron and spin-polarized electron studies, synchrotron-source x-ray scattering, etc.)

Spin momentum transfer in current perpendicular to the plane spin valves

M. Covington, A. Rebei, G. J. Parker, and M. A. Seigler

Appl. Phys. Lett. 84, 3103 (2004); http://dx.doi.org/10.1063/1.1707227 (3 pages) | Cited 3 times

Online Publication Date: 13 April 2004

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We present experimental and numerical micromagnetic data on the effect of spin momentum transfer in current perpendicular to the plane spin valves. Starting from a configuration with orthogonal free- and pinned-layer magnetizations, the free-layer magnetization exhibits abrupt current-induced switching that is qualitatively consistent with the spin torque model. When operating the spin valve as a field sensor, spin transfer can produce a change in resistance that mimics an effective magnetic field and induce magnetic instability that requires a larger bias field in order to stabilize the device. © 2004 American Institute of Physics.
Show PACS
75.70.Cn Magnetic properties of interfaces (multilayers, superlattices, heterostructures)
75.60.Ej Magnetization curves, hysteresis, Barkhausen and related effects
75.30.Cr Saturation moments and magnetic susceptibilities
75.50.Cc Other ferromagnetic metals and alloys
75.50.Ee Antiferromagnetics

Spin-dependent single-electron-tunneling effects in epitaxial Fe nanoparticles

F. Ernult, K. Yamane, S. Mitani, K. Yakushiji, K. Takanashi, Y. K. Takahashi, and K. Hono

Appl. Phys. Lett. 84, 3106 (2004); http://dx.doi.org/10.1063/1.1712035 (3 pages) | Cited 25 times

Online Publication Date: 13 April 2004

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Fe/MgO/Fe nanoparticles/MgO/Co double tunnel junctions were prepared by molecular beam epitaxy for current-perpendicular-to-plane transport measurements on submicrometer-sized pillars. Microstructural observations indicate that the samples exhibit a fully epitaxial layered structure with sharp and flat interfaces including well-defined separated Fe nanoparticles between the barriers. The introduction of asymmetric MgO tunnel barriers, i.e., with different thicknesses, in the double junction leads to a clear observation of Coulomb staircase and associated tunnel magnetoresistance oscillations. An estimation of the capacitance of the system indicates that these transport phenomena are due to charging effects of the magnetic particles. © 2004 American Institute of Physics.
Show PACS
75.50.Tt Fine-particle systems; nanocrystalline materials
75.50.Dd Nonmetallic ferromagnetic materials
73.63.Bd Nanocrystalline materials
81.07.Bc Nanocrystalline materials
75.47.Pq Other materials
73.50.Jt Galvanomagnetic and other magnetotransport effects (including thermomagnetic effects)
73.23.Hk Coulomb blockade; single-electron tunneling

Effect of sample size on magnetic Jc for MgB2 superconductor

J. Horvat, S. Soltanian, X. L. Wang, and S. X. Dou

Appl. Phys. Lett. 84, 3109 (2004); http://dx.doi.org/10.1063/1.1713031 (3 pages) | Cited 18 times

Online Publication Date: 13 April 2004

Full Text: Read Online (HTML) | Download PDF

Show Abstract
A strong effect of sample size on magnetic Jc(H) was observed for bulk MgB2 when Jc is obtained directly from the critical state model. Thus obtained zero-field Jc (Jc0) decreases strongly with the sample size, attaining a constant value for the samples larger than a few millimeters. On the other hand, the irreversibility field (Hirr) defined at Jc = 100 A/cm2 increases with the sample size. The decrease of Jc0 is described in terms of voids in the bulk MgB2 samples and superconducting screening around the cells of superconducting material between these voids (35 μm), because of concentration of the current in the narrow bridges connecting the cells. For samples larger than a few millimeters, the value of magnetic Jc is in agreement with the transport Jc and it is restricted by the voids. The critical state model is not suitable for obtaining Jc for small bulk MgB2. The increase of Hirr with the sample size is an artifact of defining Hirr by the value of Jc at which an additional superconducting screening on 1 μm scale dominates Δm. © 2004 American Institute of Physics.
Show PACS
74.25.Sv Critical currents
74.70.Ad Metals; alloys and binary compounds (including A15, MgB2, etc.)

Optical and magneto-optical studies of two-dimensional metallodielectric photonic crystals on cobalt films

M. Diwekar, V. Kamaev, J. Shi, and Z. V. Vardeny

Appl. Phys. Lett. 84, 3112 (2004); http://dx.doi.org/10.1063/1.1712027 (3 pages) | Cited 28 times

Online Publication Date: 13 April 2004

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We studied the optical transmission and magneto-optical effect through a subwavelength hole array fabricated on a ferromagnetic cobalt (Co) thin film in comparison to a control unperforated Co film having the same thickness. We found that the perforated film sustains extraordinary transmission bands through the hole array, which can be well explained as due to light coupling to surface plasmons on the two film interfaces. We also found that due to resonant coupling to the surface plasmons, the magneto-optical Kerr effect in the spectral range of the anomalous transmission bands of the perforated Co film is much smaller than that in the control Co film. © 2004 American Institute of Physics.
Show PACS
78.66.Bz Metals and metallic alloys
75.50.Cc Other ferromagnetic metals and alloys
42.70.Qs Photonic bandgap materials
78.20.Ls Magneto-optical effects
73.20.Mf Collective excitations (including excitons, polarons, plasmons and other charge-density excitations)

Faraday rotation in Co0.85Zn0.15Fe2O4 spinel ferrite nanoparticulate films under low applied fields

Richard M. Anderson, Christy R. Vestal, Anna C. S. Samia, and Z. John Zhang

Appl. Phys. Lett. 84, 3115 (2004); http://dx.doi.org/10.1063/1.1712031 (3 pages) | Cited 7 times

Online Publication Date: 13 April 2004

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Films of Co0.85Zn0.15Fe2O4 nanoparticles were prepared on silanized glass substrates using aminobenzoic acid/imidazole-modified magnetic nanoparticles. Dispersive Faraday rotations in the nanoparticulate films were observed as 1.0°–3.0° under relatively low applied magnetic field strengths of less than 500 Oe. The magnitude of the Faraday rotation increases with increasing thickness of the prepared films. No differences in the Faraday rotation were observed for Co0.85Zn0.15Fe2O4 nanoparticles as the particle size varied from 12 to 18 nm. © 2004 American Institute of Physics.
Show PACS
75.50.Gg Ferrimagnetics
61.46.-w Structure of nanoscale materials
81.07.Wx Nanopowders
75.70.Ak Magnetic properties of monolayers and thin films
78.20.Ls Magneto-optical effects

Observation of spin-transfer switching in deep submicron-sized and low-resistance magnetic tunnel junctions

Yiming Huai, Frank Albert, Paul Nguyen, Mahendra Pakala, and Thierry Valet

Appl. Phys. Lett. 84, 3118 (2004); http://dx.doi.org/10.1063/1.1707228 (3 pages) | Cited 173 times

Online Publication Date: 13 April 2004

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The spin-transfer effect has been studied in magnetic tunnel junctions (PtMn/CoFe/Ru/CoFe/Al2O3/CoFe/NiFe) with dimensions down to 0.1×0.2 μm2 and resistance–area product RA in the range of 0.5–10 Ω μm2 (ΔR/R = 1%–20%). Current-induced magnetization switching is observed with a critical current density of about 8×106 A/cm2. The attribution of the switching to the spin-transfer effect is supported by a current-induced ΔR/R value identical to the one obtained from the R versus H measurements. Furthermore, the critical switching current density has clear dependence on the applied magnetic field, consistent with what has been observed previously in the case of spin-transfer-induced switching in metallic multilayer systems. © 2004 American Institute of Physics.
Show PACS
75.70.Cn Magnetic properties of interfaces (multilayers, superlattices, heterostructures)
75.47.Np Metals and alloys
72.25.Mk Spin transport through interfaces
75.60.Ej Magnetization curves, hysteresis, Barkhausen and related effects
75.50.Bb Fe and its alloys

Thermal and electrical characterization of Cu/CoFe superlattices

Y. Yang, W. Liu, and M. Asheghi

Appl. Phys. Lett. 84, 3121 (2004); http://dx.doi.org/10.1063/1.1713033 (3 pages) | Cited 6 times

Online Publication Date: 13 April 2004

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The present work is directed at thermal and electrical characterization of the Cu/CoFe multilayer, which is made of extremely thin periodic layers, using steady-state Joule heating and thermometry in suspended bridges in the temperature range of 50–300 K. The total thickness of the layer is ds = 144 nm, while the thickness of individual repeats are 12 and 21 Å for CoFe and Cu layers, respectively. The experimental data for thermal conductivity of a 144-nm-thick single Cu layer is also presented for comparison. The experimental data indicates that the spin-dependent electron scattering at the Cu/CoFe interface contributes to a strong reduction in thermal conductivity of these layers compared to the bulk values. The calculated Lorenz numbers (from the thermal and electrical conductivity data) varies by nearly a factor 2 from 4×10−8 W Ω K−2 at 50 K to 1.8×10−8 W Ω K−2 at 300 K and is different from the free electron value of L0 = 2.45×10−8 W Ω K−2. This implies that the Wiedemann-Franz law does not hold for Cu/CoFe thin films. © 2004 American Institute of Physics.
Show PACS
75.50.Bb Fe and its alloys
75.70.Cn Magnetic properties of interfaces (multilayers, superlattices, heterostructures)
73.61.At Metal and metallic alloys
72.15.Eb Electrical and thermal conduction in crystalline metals and alloys
Return to All Sections
Close

Google Calendar

ADVERTISEMENT

Go to AIP Home   © AIP Publishing LLC
close