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Articles 1 - 13 of 13
Full-Text Articles in Physics
Microwave Absorption Of Patterned Arrays Of Nanosized Magnetic Stripes With Different Aspect Ratios, Leszek M. Malkinski, Minghui Yu, Andriy Vovk, Donald J. Scherer Ii, Leonard Spinu, Weilie Zhou, Scott L. Whittenburg, Zachary Davis, Jin-Seung Jung
Microwave Absorption Of Patterned Arrays Of Nanosized Magnetic Stripes With Different Aspect Ratios, Leszek M. Malkinski, Minghui Yu, Andriy Vovk, Donald J. Scherer Ii, Leonard Spinu, Weilie Zhou, Scott L. Whittenburg, Zachary Davis, Jin-Seung Jung
Chemistry and Biochemistry Faculty Publications
Arrays consisting of nanosized stripes of Permalloy with different length-to-width ratios have been fabricated using electron beam nanolithography, magnetron sputtering, and lift-off process. These stripes have a thickness of , a width of , and different lengths ranging from . The stripes are separated by a distance of . Magnetization hysteresis loops were measured using a superconducting quantum interference device susceptometer. Microwave absorption at was determined by means of ferromagnetic resonance technique. The dependence of the resonant field on the angle between the nanostructure and the in-plane dc magnetic field indicates the presence of uniaxial magnetic anisotropy associated with the …
Size Dependence Of Static And Dynamic Magnetic Properties In Nanoscale Square Permalloy Antidot Arrays, Minghui Yu, Leszek M. Malkinski, Leonard Spinu, Weilie Zhou, Scott L. Whittenburg
Size Dependence Of Static And Dynamic Magnetic Properties In Nanoscale Square Permalloy Antidot Arrays, Minghui Yu, Leszek M. Malkinski, Leonard Spinu, Weilie Zhou, Scott L. Whittenburg
Chemistry and Biochemistry Faculty Publications
Permalloy antidot arrays with different square hole sizes ( , , and ) have been fabricated by means of electron-beam lithography and lift-off techniques. The smaller square hole size results in enhanced remanence and reduced coercivity in the antidot array. Multiple resonance modes were clearly observed for the magnetic field applied normal to the array plane, and double uniform resonance modes occurred when the field deviated more than 30° from the normal to the plane. Two distinct dipolar field patterns with different orientations and magnitudes split the uniform resonance into double resonance modes. The double resonance modes show uniaxial in-plane …
Preparation, Structural Characterization, And Dynamic Properties Investigation Of Permalloy Antidot Arrays, Andriy Vovk, Leszek M. Malkinski, Scott L. Whittenburg, Charles O'Connor, Jin-Seung Jung, Suk-Hong Min
Preparation, Structural Characterization, And Dynamic Properties Investigation Of Permalloy Antidot Arrays, Andriy Vovk, Leszek M. Malkinski, Scott L. Whittenburg, Charles O'Connor, Jin-Seung Jung, Suk-Hong Min
Chemistry and Biochemistry Faculty Publications
Regular nanosized structures are considered to be promising materials for magnetic information storage media with high density of information. Recently attention was paid to static and dynamic magnetic properties arising from dimensional confinement in such nanostructures. Here we present an investigation of permalloy antidot arrays of different thicknesses. Thin permalloyfilms of thickness ranging from were deposited on nanoporous membranes with a pore size of . It was found that additional ferromagnetic resonance peaks appear for film thicknesses below , while films with larger thicknesses show resonanceproperties similar to continuous films. A comparison between the filmsdeposited onto Si wafers and porous …
Thickness Dependence Of Magneto-Transport In Cu-Co Granular Thin Films, Jian Qing Wang, Ngocnga Dao, Ham H. Kim, Scott L. Whittenburg
Thickness Dependence Of Magneto-Transport In Cu-Co Granular Thin Films, Jian Qing Wang, Ngocnga Dao, Ham H. Kim, Scott L. Whittenburg
Chemistry and Biochemistry Faculty Publications
This work explores the thickness dependence of magneto-transport properties in granular thin films with different thickness. These results are compared with silver-based film series studied earlier. It was observed that the thickness dependence of the GMReffect was sensitive to the surface chemistry of the films. The extraordinary Hall effect (EHE) in these films was measured and found to be different from the Ag-based system. In the Cu-based system, the EHE is a weak function of film thickness over the range studied. When the variation of the spontaneous magnetization is taken into account the effective EHE has a universal thickness dependence
Magnetic Storage Device Using Induced Magnetic Reversal Of A Cobalt Element Array, Hanning Chen, Scott L. Whittenburg
Magnetic Storage Device Using Induced Magnetic Reversal Of A Cobalt Element Array, Hanning Chen, Scott L. Whittenburg
Chemistry and Biochemistry Faculty Publications
The effects of the applied field, cell size, and cutting area on the ‘‘seed’’ induced magnetic reversal of a cobalt element array have been studied by a stochastic dynamic micromagnetics code using the Laudau–Lifshitz–Gilbert equation. Three magnetic reversal mechanisms under different magnitudes of the applied field have been investigated by examining the energy profiles. To minimize the effect of the thermal fluctuations on the switching time, an applied field with magnitude around 0.7 or 0.8 T and an element array with cutting area less than 10 nm X 10 nm are required. By using the smaller cellsize, the switching time …
Thickness Dependence Of Magnetic Blocking In Granular Thin Films With Interacting Magnetic Particles, Jian Qing Wang, Zhi Dong Zhao, Scott L. Whittenburg
Thickness Dependence Of Magnetic Blocking In Granular Thin Films With Interacting Magnetic Particles, Jian Qing Wang, Zhi Dong Zhao, Scott L. Whittenburg
Chemistry and Biochemistry Faculty Publications
Interparticle interaction among single domain nanosize magnetic particles embedded in nonmagnetic matrix was studied. Attention was paid to concentrated Cu–Co granular thin films with a fixed magnetic volume fraction (20%). By analyzing theoretical models and comparing with experimental results, a dimensional constraint on the magnetic properties was found. As the film thickness reduces toward the thin limit the interparticle interaction plays important roles in modifying the magnetic behavior. The dipolar interaction energy was calculated among magnetic particles including far-neighbor interaction for films with different thickness values. When magnetization variation is included in the calculation, the resulting calculated interaction energy versus …
Monte Carlo Simulation On The Indirect Exchange Interactions Of Co-Doped Zno Film, Abraham F. Jalbout, Hanning Chen, Scott L. Whittenburg
Monte Carlo Simulation On The Indirect Exchange Interactions Of Co-Doped Zno Film, Abraham F. Jalbout, Hanning Chen, Scott L. Whittenburg
Chemistry and Biochemistry Faculty Publications
Monte Carlo simulations using a three-dimensional lattice model studied the Ruderman–Kittel–Kasuya–Yosida (RKKY) indirect exchange interaction of doped magnetic Co ions in ZnOfilms. The results of the calculations show that the RKKY interaction in Co-doped ZnO is long ranged and its magnitude is proportional to (inverse of the distance from a central ion). The sign oscillates with a frequency that depends on the concentration of the carrier. The long-distance sum of the RKKY indirect exchange energies is positive indicating that these materials are ferromagnetic, in direct correlation with previously reported results.
Magnetization Reversal Of Elliptical Co/Cu/Co Pseudo-Spin Valve Dots, Ngocnga Dao, Scott L. Whittenburg, Y. Hao, Leszek M. Malkinski, Jian Qing Wang, C. A. Ross
Magnetization Reversal Of Elliptical Co/Cu/Co Pseudo-Spin Valve Dots, Ngocnga Dao, Scott L. Whittenburg, Y. Hao, Leszek M. Malkinski, Jian Qing Wang, C. A. Ross
Chemistry and Biochemistry Faculty Publications
We present our recent simulated results on Cr (5 nm)/ Cu (5 nm)/ Co (5 nm)/ Cu (3 nm)/ Co (2 nm) pseudo-spin valve dots. The simulated results agree qualitatively with the experimental results. Three different sizes of elliptical dots, and were simulated. Our simulations show that in these types of dots magnetization reversal occurs by the formation of domain walls: for and for No domain wall was observed in the reversal of the dots. For such dots, the simulated loops show a small two-step reversal pattern with the thin upper layer partially reversing followed by complete reversal of both …
Micromagnetics Simulation Of Nanoshaped Iron Elements: Comparison With Experiment, Ngocnga Dao, S. R. Homer, Scott L. Whittenburg
Micromagnetics Simulation Of Nanoshaped Iron Elements: Comparison With Experiment, Ngocnga Dao, S. R. Homer, Scott L. Whittenburg
Chemistry and Biochemistry Faculty Publications
A micromagnetics simulation has been conducted on nanostructured magnetic elements of iron in order to investigate the effect of the shape of the element on magnetic properties, such as domain formation and hysteresis loops. These results are compared with recent experimental studies. The results display an impressive agreement with both the experimentally observed magnetic domains in individual particles as well as the shape of the hysteresis loops. The simulation results then explain features in the hysteresis loops in terms of vortice formation and motion.
Studies Of The Reorientational Relaxation Of Pyridine In Water By Depolarized Rayleigh Light Scattering, C. H. Wang, Scott L. Whittenburg, P. A. Lund, D. H. Christensen
Studies Of The Reorientational Relaxation Of Pyridine In Water By Depolarized Rayleigh Light Scattering, C. H. Wang, Scott L. Whittenburg, P. A. Lund, D. H. Christensen
Chemistry and Biochemistry Faculty Publications
The depolarized Rayleigh spectra of aqueous solutions of pyridine have been studied using a high‐finesse Fabry–Perot interferometer as a function of temperature and concentration. The Rayleigh relaxation times are found to have a complex concentration and viscosity dependence. The classical Stokes–Einstein–Debye equation for molecular reorientation breaks down in this system. The Rayleigh relaxation time of pyridine molecules is not determined by the macroscopic shear viscosity of the solution. The specific interaction due to the formation of hydrogen bonds between pyridine and water molecules plays a very important role in affecting the relaxation time. At a fixed temperature the plot of …
Light Scattering Studies Of Transverse Sound Wave And Molecular Motion In Benzonitrile, Scott L. Whittenburg, C. H. Wang
Light Scattering Studies Of Transverse Sound Wave And Molecular Motion In Benzonitrile, Scott L. Whittenburg, C. H. Wang
Chemistry and Biochemistry Faculty Publications
The zero‐frequency shear wave dip appearing in the depolarized Rayleigh spectrum in benzonitrile has been studied as a function of concentration and temperature. The solution study was carried out at constant viscosity equal to the viscosity of liquid benzonitrile at each temperature. The result indicates that the presence of shear wave fine structure does not depend on the collective orientational fluctuations. The orientational and vibrational relaxation times of benzonitrile were measured at various concentrations and temperatures. The orientational relaxation times show no concentration dependence at any temperature, suggesting that the pair correlation is negligible at all concentrations. The orientational relaxation …
Light Scattering Studies Of Rotational And Vibrational Relaxations Of Acetonitrile In Carbon Tetrachloride, Scott L. Whittenburg, C. H. Wang
Light Scattering Studies Of Rotational And Vibrational Relaxations Of Acetonitrile In Carbon Tetrachloride, Scott L. Whittenburg, C. H. Wang
Chemistry and Biochemistry Faculty Publications
The rotational and vibrational relaxation times of acetonitrile–carbon tetrachloride solutions were investigated as a function of concentration, viscosity, and temperature using depolarized Rayleigh and Raman scattering. Using a Fabry‐Perot interferometer and single frequency laser source, we have shown that reliable results for the single particle orientational correlation times (τs) for CH3CN can be obtained by carrying out a concentration dependent depolarized Rayleigh scattering study. Raman scattering was shown to yield inconsistent results for τs in CH3CN. At constant viscosity, it was found that the Rayleigh scatteringrelaxation time (τRay) of CH3 …
A Comparison Of The Rough Sphere Rotational Diffusion Model With Experimental Results For Liquid Methyl Iodide, Dane R. Jones, Scott L. Whittenburg, C. H. Wang
A Comparison Of The Rough Sphere Rotational Diffusion Model With Experimental Results For Liquid Methyl Iodide, Dane R. Jones, Scott L. Whittenburg, C. H. Wang
Chemistry and Biochemistry Faculty Publications
No abstract available.