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

24 Jan 2011

Volume 98, Issue 4, Articles (04xxxx)

Issue Cover Spotlight Figure

Appl. Phys. Lett. 98, 043101 (2011); http://dx.doi.org/10.1063/1.3536475 (3 pages)

Zhichao Ruan and Shanhui Fan
Enlarge Image | Read More
Return to All Sections
back to top
RSS Feeds

Magnetic microstructure and magnetotransport in Co2FeAl Heusler compound thin films

Mathias Weiler, Franz D. Czeschka, Andreas Brandlmaier, Inga-Mareen Imort, Günter Reiss, Andy Thomas, Georg Woltersdorf, Rudolf Gross, and Sebastian T. B. Goennenwein

Appl. Phys. Lett. 98, 042501 (2011); http://dx.doi.org/10.1063/1.3544559 (3 pages) | Cited 1 time

Online Publication Date: 24 January 2011

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We correlate simultaneously recorded magnetotransport and spatially resolved magneto-optical Kerr effect (MOKE) data in Co2FeAl Heusler compound thin films micropatterned into Hall bars. Room temperature MOKE images reveal the nucleation and propagation of domains in an externally applied magnetic field and are used to extract a macrospin corresponding to the mean magnetization direction in the Hall bar. The anisotropic magnetoresistance calculated using this macrospin is in excellent agreement with magnetoresistance measurements. This suggests that the magnetotransport in Heusler compounds can be adequately simulated using simple macrospin models, while the magnetoresistance contribution due to domain walls is of negligible importance.
Show PACS
75.70.Ak Magnetic properties of monolayers and thin films
75.25.-j Spin arrangements in magnetically ordered materials (including neutron and spin-polarized electron studies, synchrotron-source x-ray scattering, etc.)
78.66.Bz Metals and metallic alloys
75.60.Ej Magnetization curves, hysteresis, Barkhausen and related effects
78.20.Ls Magneto-optical effects
72.15.Gd Galvanomagnetic and other magnetotransport effects

Kinetic depinning of a magnetic domain wall above the Walker field

E. R. Lewis, D. Petit, L. O’Brien, A.-V. Jausovec, H. T. Zeng, D. E. Read, and R. P. Cowburn

Appl. Phys. Lett. 98, 042502 (2011); http://dx.doi.org/10.1063/1.3543844 (3 pages) | Cited 4 times

Online Publication Date: 24 January 2011

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The dynamical interaction between a transverse domain wall and a T-shaped trap is investigated, for domain wall motion in the oscillatory regime above the Walker field. We demonstrate experimentally the existence of distinct static and kinetic depinning fields in this regime, and show that the oscillatory motion of the domain wall leads to a distribution of kinetic depinning fields. Micromagnetic simulations are in good qualitative agreement with our experimental results.
Show PACS
75.78.Fg Dynamics of domain structures
75.78.Cd Micromagnetic simulations
75.60.Ch Domain walls and domain structure

Effect of the number of layers on determination of spin asymmetries in current-perpendicular-to-plane giant magnetoresistance

Tomohiro Taniguchi, Hiroshi Imamura, Tomoya M. Nakatani, and Kazuhiro Hono

Appl. Phys. Lett. 98, 042503 (2011); http://dx.doi.org/10.1063/1.3531758 (3 pages)

Online Publication Date: 24 January 2011

Full Text: Read Online (HTML) | Download PDF


See Also: Erratum

Show Abstract
Current-perpendicular-to-plane giant-magnetoresistance effect in a ferromagnetic/nonmagnetic multilayer is studied theoretically by solving the diffusion equation of the spin accumulation without assuming the periodic boundary condition. We show that the Valet and Fert theory underestimates spin asymmetries with decreasing the number of layers.
Show PACS
75.47.De Giant magnetoresistance
75.70.Cn Magnetic properties of interfaces (multilayers, superlattices, heterostructures)

Low spin current-driven dynamic excitations and metastability in spin-valve nanocontacts with unpinned artificial antiferromagnet

M. Eggeling, T. Dimopoulos, T. Uhrmann, O. Bethge, R. Heer, V. Höink, and H. Brückl

Appl. Phys. Lett. 98, 042504 (2011); http://dx.doi.org/10.1063/1.3537953 (3 pages) | Cited 1 time

Online Publication Date: 24 January 2011

Full Text: Read Online (HTML) | Download PDF

Show Abstract
This work investigates the spin-torque-related dynamics of nonuniform magnetic vortexlike states in spin-valve nanocontacts, employing an unpinned artificial antiferromagnet as polarizer and amorphous CoFeB as free layer. Subgigahertz spectra are obtained for contacts of 150–200 nm in diameter. Low critical current density and reversibility of the dynamic spectra with respect to the current are obtained. The spectral power and linewidth depend on the in-plane magnetic field, assuming maximum, respectively minimum, values within the free layer’s magnetization switching. For certain field and current windows metastable dynamic states are clearly demonstrated.
Show PACS
75.70.Cn Magnetic properties of interfaces (multilayers, superlattices, heterostructures)
75.50.Ee Antiferromagnetics
75.30.Ds Spin waves
75.60.Ej Magnetization curves, hysteresis, Barkhausen and related effects
81.07.Lk Nanocontacts
75.75.-c Magnetic properties of nanostructures

Nonlinear amplification and mixing of spin waves in a microstrip geometry with metallic ferromagnets

Yuri Khivintsev, J. Marsh, V. Zagorodnii, I. Harward, J. Lovejoy, P. Krivosik, R. E. Camley, and Z. Celinski

Appl. Phys. Lett. 98, 042505 (2011); http://dx.doi.org/10.1063/1.3541787 (3 pages) | Cited 3 times

Online Publication Date: 24 January 2011

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We explore the nonlinear mixing and amplification of magnetic polariton modes in ultrasmall waveguides. Ultrasmall waveguide geometries can produce large oscillating microwave fields—up to about 500 Oe. Using these large fields, we examine nonlinear ferromagnetic dynamics in ribbons of Permalloy and Fe. In particular if two microwave signals at different frequencies are sent into the waveguide, we can increase the transmission of one wave by adding energy to the other wave. We also demonstrate the creation of new frequencies and the development of a comb of equally spaced frequencies. These experimental results are explained with perturbation theory and micromagnetics calculations.
Show PACS
85.70.-w Magnetic devices
84.40.Az Waveguides, transmission lines, striplines

Study and tailoring spin dynamic properties of CoFeB during rapid thermal annealing

Yaping Zhang, Xin Fan, Weigang Wang, Xiaoming Kou, Rong Cao, Xing Chen, Chaoying Ni, Liqing Pan, and John Q. Xiao

Appl. Phys. Lett. 98, 042506 (2011); http://dx.doi.org/10.1063/1.3549188 (3 pages) | Cited 4 times

Online Publication Date: 26 January 2011

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We studied the real-time evolution of magnetic dynamic and static properties of 20 nm CoFeB thin film during annealing at 380 °C. The ferromagnetic resonance linewidth quickly reduces by 30% within 300 s annealing, and monotonically increases upon longer annealing. The magnetic static coercivity shows similar trend. The underlying physical relation between linewidth and anisotropy can be connected by the two-magnon scattering theory. By doping of Nb into CoFeB films, the damping was maintained at a low value within 2000 s annealing. This method to tailor the dynamic properties of CoFeB may benefit the development of magnetics and spintronics based microwave devices.
Show PACS
75.70.Ak Magnetic properties of monolayers and thin films
75.60.Ej Magnetization curves, hysteresis, Barkhausen and related effects
75.40.Gb Dynamic properties (dynamic susceptibility, spin waves, spin diffusion, dynamic scaling, etc.)
76.50.+g Ferromagnetic, antiferromagnetic, and ferrimagnetic resonances; spin-wave resonance
75.30.Gw Magnetic anisotropy
61.72.Cc Kinetics of defect formation and annealing

The effect of Co substitution on the magnetic properties of the Heusler alloy Ni50Mn33Sn17

R. Y. Umetsu, A. Sheikh, W. Ito, B. Ouladdiaf, K. R. A. Ziebeck, T. Kanomata, and R. Kainuma

Appl. Phys. Lett. 98, 042507 (2011); http://dx.doi.org/10.1063/1.3548558 (3 pages) | Cited 4 times

Online Publication Date: 26 January 2011

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Magnetic measurements and neutron powder diffraction experiments on Ni50Mn33Sn17 and Ni45Co5Mn33Sn17 alloys were performed in order to establish the magnetic structures and the effects of Co substitution on the magnetic properties. It was shown that the magnetic coupling between the Mn moments on the 4a and 4b sites changed from being antiferromagnetic to ferromagnetic by substitution of Co. As a result of the change in the magnetic structure due to the Co substitution, the ferromagnetic properties of Ni–Co–Mn–Sn are enhanced. These results have enabled the concentration dependence of the magnetic moment to be quantified.
Show PACS
75.30.Cr Saturation moments and magnetic susceptibilities
75.50.Ee Antiferromagnetics
75.25.-j Spin arrangements in magnetically ordered materials (including neutron and spin-polarized electron studies, synchrotron-source x-ray scattering, etc.)
75.50.Cc Other ferromagnetic metals and alloys

Enhanced critical current properties in Ba0.6K0.4+xFe2As2 superconductor by overdoping of potassium

Chunlei Wang, Lei Wang, Zhaoshun Gao, Chao Yao, Dongliang Wang, Yanpeng Qi, Xianping Zhang, and Yanwei Ma

Appl. Phys. Lett. 98, 042508 (2011); http://dx.doi.org/10.1063/1.3549195 (3 pages) | Cited 3 times

Online Publication Date: 27 January 2011

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Phase-pure polycrystalline Ba0.6K0.4+xFe2As2 with 0 ≤ x ≤ 0.1 were prepared using a one-step solid-state reaction method. We found that overdoping of potassium can improve the critical current density (Jc). High-field Jc for samples with x = 0.1 is three times higher than that for samples with x = 0. Overdoping of K has minimal effect on the critical transition temperature (Tc). Less than 0.5 K degradations in Tc was measured for samples with x = 0.1. Transmission electron microscopy (TEM) revealed high concentration of dislocations in samples with x = 0.1, resulting in enhanced flux pining. Further analyses on magnetization loops for powder samples confirm that K overdoping can promote intragrain Jc. Our results indicate that slight excess of K in Ba0.6K0.4Fe2As2 superconductor is beneficial to high-field applications.
Show PACS
74.25.Sv Critical currents
74.70.Xa Pnictides and chalcogenides
74.25.Wx Vortex pinning (includes mechanisms and flux creep)
61.72.Ff Direct observation of dislocations and other defects (etch pits, decoration, electron microscopy, x-ray topography, etc.)
74.25.Ha Magnetic properties including vortex structures and related phenomena

Self-assembled oxide nanopillars in epitaxial BaFe2As2 thin films for vortex pinning

Yi Zhang, Christopher T. Nelson, Sanghan Lee, Jianyi Jiang, Chung Wung Bark, Jeremy D. Weiss, Chiara Tarantini, Chad M. Folkman, Seung-Hyub Baek, Eric E. Hellstrom, David C. Larbalestier, Chang-Beom Eom, and Xiaoqing Pan

Appl. Phys. Lett. 98, 042509 (2011); http://dx.doi.org/10.1063/1.3532107 (3 pages) | Cited 9 times

Online Publication Date: 27 January 2011

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We report the structure and chemistry of the self-assembled oxide nanopillars that form in superconducting Co-doped BaFe2As2 thin film grown by pulsed laser deposition. The oxide nanopillars consist of a BaFeO2 phase, form epitaxially on the SrTiO3 template, and grow coherently with the BaFe2As2 film. The nanopillars are square with a uniform size of 4–5 nm, which is close to twice the superconducting coherence length. Despite a volume content of ∼ 5%, the nanopillars do not degrade the structural quality of the BaFe2As2 matrix. Indeed the nanopillars provide exceptionally strong vortex pinning and high critical current density due to the very close correlation of pillar and vortex core diameters.
Show PACS
74.25.Wx Vortex pinning (includes mechanisms and flux creep)
81.16.Dn Self-assembly
74.78.Na Mesoscopic and nanoscale systems
81.15.Fg Pulsed laser ablation deposition

Magnetization reversal in exchange biased IrMn/Fe ring arrays

Yu-feng Hou, Qing-feng Zhan, and Kannan M. Krishnan

Appl. Phys. Lett. 98, 042510 (2011); http://dx.doi.org/10.1063/1.3549187 (3 pages) | Cited 2 times

Online Publication Date: 28 January 2011

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We investigated the effect of exchange bias on the magnetization reversal behavior in ring-shaped IrMn/Fe lithographic structures. The magnetic anisotropy geometry of the exchange biased ring is revealed by fitting for the angular dependence of the exchange bias, Heb, and coercivity, Hc. Magnetic force microscopy images obtained at different field values along the hysteresis loop show that along the bias direction, the ring exhibits a magnetic reversal via nonuniform domain nucleation while perpendicular to the bias direction, the magnetic reversal occurs via coherent rotation. The difference in magnetic switching modes for these two field orientations is confirmed by micromagnetic simulations and interpreted by the effective field model.
Show PACS
75.70.Cn Magnetic properties of interfaces (multilayers, superlattices, heterostructures)
75.30.Gw Magnetic anisotropy
75.30.Et Exchange and superexchange interactions
75.60.Jk Magnetization reversal mechanisms
75.60.Ch Domain walls and domain structure
75.78.Cd Micromagnetic simulations

Transport properties of the new Fe-based superconductor KxFe2Se2 (Tc = 33 K)

Yoshikazu Mizuguchi, Hiroyuki Takeya, Yasuna Kawasaki, Toshinori Ozaki, Shunsuke Tsuda, Takahide Yamaguchi, and Yoshihiko Takano

Appl. Phys. Lett. 98, 042511 (2011); http://dx.doi.org/10.1063/1.3549702 (3 pages) | Cited 23 times

Online Publication Date: 28 January 2011

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We synthesized the new Fe-based superconductor K0.8Fe2Se2 single crystals. The obtained single crystal exhibited a sharp superconducting transition and the onset and zero-resistivity tempera-ture were estimated to be 33 and 31.8 K, respectively. A high upper critical field of 192 T was obtained. The anisotropy of superconductivity of K0.8Fe2Se2 was ∼ 3.6. Both the high upper critical field and comparably low anisotropy are advantageous for applications under a high magnetic field.
Show PACS
74.25.F- Transport properties
74.70.-b Superconducting materials other than cuprates
74.25.Dw Superconductivity phase diagrams
74.25.Ha Magnetic properties including vortex structures and related phenomena
Return to All Sections
Close

Google Calendar

ADVERTISEMENT

Go to AIP Home   © AIP Publishing LLC
close