jap banner
  • Volume/Page
  • Keyword
  • DOI
  • Citation
  • Advanced
   
 
 
 

Flickr Twitter iResearch App Facebook

SECTION LISTING

BROWSE VOLUMES

Year Range: 
Search Issue | RSS Feeds RSS
Previous Issue Next Issue

15 May 2003

Volume 93, Issue 10, pp. 5855-8792

Return to All Sections
back to top
RSS Feeds

Spin-wave frequency discretization in submicron rectangular prisms

G. Gubbiotti, P. Candeloro, L. Businaro, E. Di Fabrizio, A. Gerardino, R. Zivieri, M. Conti, and G. Carlotti

J. Appl. Phys. 93, 7595 (2003); http://dx.doi.org/10.1063/1.1544478 (3 pages) | Cited 9 times

Online Publication Date: 9 May 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Spin-wave frequency discretization has been observed by Brillouin light scattering in an array of tangentially magnetized 800 nm×550 nm Ni81Fe19 rectangular prisms with thicknesses of 30 nm and dot separations of 200 nm. For a large wave vector interval, several discrete dispersionless modes were observed. The experimental frequencies were compared to those calculated using a recently developed analytical model for flat uniformly magnetized rectangular prisms. The agreement between the experimental and calculated frequencies is very good. In addition to the above mentioned modes, a low frequency mode was experimentally detected over a wide range of transferred wave vectors. Finally, the decrease in frequency of the first perpendicular standing spin-wave mode, observed in the patterned sample with respect to in the continuous film, was successfully reproduced. © 2003 American Institute of Physics.
Show PACS
75.30.Ds Spin waves
75.50.Bb Fe and its alloys
78.35.+c Brillouin and Rayleigh scattering; other light scattering
78.20.Ls Magneto-optical 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

Nonuniform demagnetizing field and magnetization in element of patterned NiFe films

Y. Zhai, J. Li, Y. Yan, X. Y. Zhang, M. Lu, H. R. Zhai, and J. Shi

J. Appl. Phys. 93, 7598 (2003); http://dx.doi.org/10.1063/1.1555313 (3 pages) | Cited 5 times

Online Publication Date: 9 May 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Patterned arrays of micron and submicron rectangular Ni81Fe19 elements studied by ferromagnetic resonance (FMR) previously showed that an in-plane shape anisotropy existed in the element, with two origins. One is contributed from a quasiuniform magnetization described by conventional demagnetizing factors, another is an effect of the non-uniform magnetization in the nonellipsoidal element. The results of micromagnetic numerical calculation provide further evidence of the nonuniform demagnetizing field and nonuniform magnetization in the rectangular elements. The calculated profile of demagnetizing field shows that as the aspect ratio increases the non-uniform demagnetizing field decreases, as the data of in-plane FMR require. When the static field is not along either of the edges the demagnetizing field become more nonuniform. Not only its magnitude but also its direction is nonuniform, which causes nonuniform static and microwave field and thus meets the condition for magnetostatic mode excitation as observed by FMR. When the field is along the film normal, the demagnetizing fields at the film edges differ much from the uniform field in the central portion and the magnetization changes gradually across the side. These meet the requirement of dynamic pinning and the excitation of the spin waves with k vector along the narrow side of the elements that was observed by FMR. © 2003 American Institute of Physics.
Show PACS
75.70.Ak Magnetic properties of monolayers and thin films
75.60.Ej Magnetization curves, hysteresis, Barkhausen and related effects
76.50.+g Ferromagnetic, antiferromagnetic, and ferrimagnetic resonances; spin-wave resonance
75.30.Gw Magnetic anisotropy
75.30.Ds Spin waves

Thermal spin excitations in epitaxial Fe nanostructures on GaAs(001)

W. Kipferl, M. Dumm, M. Rahm, and G. Bayreuther

J. Appl. Phys. 93, 7601 (2003); http://dx.doi.org/10.1063/1.1555314 (3 pages) | Cited 14 times

Online Publication Date: 9 May 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Thermal spin excitations in confined ferromagnetic structures become increasingly important, e.g., because they reduce tunnel magnetoresistance in highly integrated magnetic memories and the stability of stored information. Here, the effect of lateral confinement on the temperature dependence of magnetization in ultrathin films was studied. Epitaxial Fe films were grown on GaAs(001) by molecular beam epitaxy. Patterning into dot arrays with several million dots of well defined circular shape was accomplished by electron beam lithography, lift-off, and ion beam etching. The magnetic properties of the samples were investigated by superconducting quantum interference device magnetometry between 10 and 350 K. All films—in addition to the fourfold magnetocrystalline anisotropy—have an in-plane uniaxial magnetic anisotropy with the easy axis along [110], which is fully conserved during patterning. The temperature dependence of the spontaneous magnetization for T<0.5TC can be well described by Bloch’s law, MS(T)=M(0)(1−BT3/2), for all samples. For a dot diameter of 500 nm the spin wave parameter B is significantly increased compared to the extended 14 ML film, which in turn shows about twice the bulk value of BFe=5×10−6 K−3/2. The enhancement of spin wave excitations with decreasing film thickness and lateral dimension is discussed in comparison to existing theories and model simulations. © 2003 American Institute of Physics.
Show PACS
75.75.-c Magnetic properties of nanostructures
75.50.Bb Fe and its alloys
75.70.Ak Magnetic properties of monolayers and thin films
75.30.Ds Spin waves
75.30.Gw Magnetic anisotropy
75.60.Ej Magnetization curves, hysteresis, Barkhausen and related effects

Spin-wave modes in magnetic nanowires

R. Skomski, M. Chipara, and D. J. Sellmyer

J. Appl. Phys. 93, 7604 (2003); http://dx.doi.org/10.1063/1.1558691 (3 pages) | Cited 9 times

Online Publication Date: 9 May 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Spin-wave modes in magnetic transition-metal nanowires having diameters of about 10 nm and lengths on the order of 1 μm are investigated by model calculations. There are quasicontinuous modes with k vectors parallel to the wires axis and discrete modes with k vectors perpendicular to the wire axis. Due to the small cross section of the wires, the perpendicular modes can be ignored in many cases and the low-temperature behavior of the wires is quasi one-dimensional. Using an analytic approach and exploiting the analogy between micromagnetism and quantum mechanics it is shown that all spin-wave modes with k vectors parallel to the wire axis are localized. The spin-wave localization is a micromagnetic analog to the Anderson localization of conduction electrons due to randomness in less than two dimensions, and, as in the electron analogy, arbitrarily small disorder is sufficient to cause the localization of all modes. © 2003 American Institute of Physics.
Show PACS
75.30.Ds Spin waves
75.40.Gb Dynamic properties (dynamic susceptibility, spin waves, spin diffusion, dynamic scaling, etc.)
75.75.-c Magnetic properties of nanostructures

Spin wave modes in submicron cylindrical dots

G. Gubbiotti, G. Carlotti, R. Zivieri, F. Nizzoli, T. Okuno, and T. Shinjo

J. Appl. Phys. 93, 7607 (2003); http://dx.doi.org/10.1063/1.1544481 (3 pages) | Cited 12 times

Online Publication Date: 9 May 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The dynamic properties of a squared array of cylindrical Ni81Fe19 dots with thickness L=50 nm, radius R=100 nm, and separation 2R have been investigated by Brillouin light scattering. The sample was prepared by means of electron-beam lithography and evaporation in ultrahigh vacuum. The lateral confinement of spin waves within each dot causes a marked discretization of the spin wave spectrum. Several discrete peaks were measured in the saturated state as a function of both the incidence angle of light and the applied magnetic field. The detected modes are classified as surface dipolar and bulk magnetostatic modes at frequencies higher and lower than the Kittel uniform mode, respectively. © 2003 American Institute of Physics.
Show PACS
75.75.-c Magnetic properties of nanostructures
75.30.Ds Spin waves
78.35.+c Brillouin and Rayleigh scattering; other light scattering
75.50.Bb Fe and its alloys
75.40.Gb Dynamic properties (dynamic susceptibility, spin waves, spin diffusion, dynamic scaling, etc.)
75.50.Tt Fine-particle systems; nanocrystalline materials

Magnetotransport properties of lithographically defined lateral Co/Ni80Fe20 wires

M. K. Husain and A. O. Adeyeye

J. Appl. Phys. 93, 7610 (2003); http://dx.doi.org/10.1063/1.1540179 (3 pages) | Cited 1 time

Online Publication Date: 9 May 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
In this article we have investigated the magnetization reversal process of laterally defined coupled magnetic structures consisting of micron-sized sputtered Co and Ni80Fe20 wires lying side by side at temperatures ranging from 3 to 300 K. We have used a microfabrication technique to create an array of planar, laterally coupled magnetic wires made of two ferromagnetic materials. We observed two distinct peaks in the magnetoresistance (MR) curves corresponding to the magnetization reversals of Co and Ni80Fe20 wires. Below a critical temperature of 20 K we observed an asymmetric shift in the Ni80Fe20 peak position for both forward and reverse field sweeps due to the exchange coupling between the ferromagnetic (Ni80Fe20) and antiferromagnetic (Co–oxide at the interface of Co and Ni80Fe20 formed during fabrication) parts. The Co peaks gradually disappeared as the temperature was reduced. At low temperature we also observed that the Ni80Fe20 peaks in the MR loops are considerably shifted to larger fields corresponding to the increase in coercivity. © 2003 American Institute of Physics.  
Show PACS
75.70.Cn Magnetic properties of interfaces (multilayers, superlattices, heterostructures)
75.60.Jk Magnetization reversal mechanisms
75.47.De Giant magnetoresistance
75.50.Bb Fe and its alloys
75.50.Cc Other ferromagnetic metals and alloys
75.30.Et Exchange and superexchange interactions

Switching behavior of cross contacting current perpendicular to plane giant magnetoresistance structure fabricated by two-step ion milling technique

H. Oishi, Y. Nozaki, and K. Matsuyama

J. Appl. Phys. 93, 7613 (2003); http://dx.doi.org/10.1063/1.1544450 (3 pages) | Cited 1 time

Online Publication Date: 9 May 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
A current perpendicular to plane giant magnetoresistance structure with a cross contact geometry was fabricated by a two-step ion-milling technique. Multilayer pillars with various layer structures and a lateral dimension down to 0.4 μm were embedded between orthogonal top and bottom electrodes. The microfabricated cross point structure minimizes the influence of electrode resistance in measurements of magnetoresistance in current perpendicular to plane geometry. Individual switching of Co layer was observed in a pillar with layer structure of [Co(10 nm)/Cu(4 nm)/Co(2 nm)/Cu(10 nm)]3 and lateral dimension of 0.4×2.0 μm2. Distinct three-step resistance change was observed for the rising part of the magnetoresistance (MR) curve, corresponding to the switching of Co(2 nm) layers. Somewhat complicated MR behavior in the falling part suggests the existence of a local minimum configuration during the switching of Co(10 nm) layers. The switching behavior of magnetic layers with interlayer dipole coupling was studied by micromagnetic simulations. Markedly different switching field of Co layers can be attributable to the variation of the dipole fields at each layer. © 2003 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

Magnetotransport properties of bent ferromagnetic nanowires

M. Tanase, D. M. Silevitch, C. L. Chien, and D. H. Reich

J. Appl. Phys. 93, 7616 (2003); http://dx.doi.org/10.1063/1.1556205 (3 pages) | Cited 4 times

Online Publication Date: 9 May 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Magnetotransport measurements were performed on individual multisegmented Pt–Ni–Pt nanowires fabricated by electrochemical deposition in nanoporous alumina templates. The nanowires were removed from the template, and precipitated onto substrates from liquid suspension. The Pt end segments provide an oxide-free interface to the magnetic central segment of interest. Centrifugation prior to precipitation induces sharp bends in the nanowires. The angular dependence of the magnetoresistance of both straight and bent nanowires was used to observe domain switching. The magnetic response of straight nanowires is well described by the curling model of domain reversal. In the case of the bent nanowires, the general behavior of each individual straight segment is also consistent with this model, but evidence for interactions between the segments is also observed. © 2003 American Institute of Physics.
Show PACS
75.75.-c Magnetic properties of nanostructures
75.50.Cc Other ferromagnetic metals and alloys
75.47.Pq Other materials
75.60.Ch Domain walls and domain structure
75.50.Tt Fine-particle systems; nanocrystalline materials
61.46.-w Structure of nanoscale materials

Magnetoresistance study in NiFe semicircle-ring patterned wires

C. Yu, S. F. Lee, Y. D. Yao, Y. R. Ma, E. W. Huang, J. L. Tsai, T. Y. Chen, and C. R. Chang

J. Appl. Phys. 93, 7619 (2003); http://dx.doi.org/10.1063/1.1556935 (3 pages) | Cited 4 times

Online Publication Date: 9 May 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Micron size NiFe wire having a patterned shape of semicircle in series was fabricated. Magnetoresistance of the wire has been studied from 10 to 300 K. Domain wall resistivity is nearly independent of the temperature; however, the domain wall switching field decreases relatively rapidly with increasing temperature. We have observed experimentally two distinct domain structures at the corners of the NiFe semicircle-ring patterned wire at remanence after longitudinal and transverse saturation fields. We can explain successfully the magnetization reversal process on the magnetoresistance loops by the contribution from anisotropic magnetoresistance and magnetic domain configuration. © 2003 American Institute of Physics.
Show PACS
72.15.Gd Galvanomagnetic and other magnetotransport effects
75.50.Bb Fe and its alloys
75.60.Ch Domain walls and domain structure
75.60.Jk Magnetization reversal mechanisms
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