Open Access. Powered by Scholars. Published by Universities.®

Physics Commons™

Open Access. Powered by Scholars. Published by Universities.®

University of New Orleans

2007

Articles 1 - 8 of 8

Full-Text Articles in Physics

Quarter-Wave Layers With 50% Reflectance For Obliquely Incident Unpolarized Light, R. M.A. Azzam, F. F. Sudradjat Feb 2007

Quarter-Wave Layers With 50% Reflectance For Obliquely Incident Unpolarized Light, R. M.A. Azzam, F. F. Sudradjat

Electrical Engineering Faculty Publications

The conditions under which light interference in a transparent quarter-wave layer of refractive index n1 on a transparent substrate of refractive index n2 leads to 50% reflectance for incident unpolarized light at an angle φ are determined. Two distinct solution branches are obtained that correspond to light reflection above and below the polarizing angle, φp , of zero reflection for p polarization. The real p and s amplitude reflection coefficients have the same (negative) sign for the solution branch φ>φp and have opposite signs for the solution branch φ<φp . Operation at φ<φp is the basis of a 50%–50% beam splitter that divides an incident totally polarized light beam (with p and s components of equal intensity) into reflected and …

Go to article

Polarizing Properties Of Embedded Symmetric Trilayer Stacks Under Conditions Of Frustrated Total Internal Reflection, Rasheed M.A. Azzam, Siva R. Perla Jan 2007

Polarizing Properties Of Embedded Symmetric Trilayer Stacks Under Conditions Of Frustrated Total Internal Reflection, Rasheed M.A. Azzam, Siva R. Perla

Electrical Engineering Faculty Publications

An error in the application of the design procedure described in a previous paper [Appl. Opt. 45, 1650 (2006)] has been corrected, and new revised figures are included in this erratum.

Go to article

Size Dependence Of Static And Dynamic Magnetic Properties In Nanoscale Square Permalloy Antidot Arrays, Minghui Yu, Leszek Malkinski, Leonard Spinu, Weillie Zhou, Scott Whittenburg Jan 2007

Size Dependence Of Static And Dynamic Magnetic Properties In Nanoscale Square Permalloy Antidot Arrays, Minghui Yu, Leszek Malkinski, Leonard Spinu, Weillie Zhou, Scott Whittenburg

Physics Faculty Publications

Permalloy antidot arrays with different square hole sizes (1200×1200, 800×800, and 400×400 nm2) 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 …

Go to article

Enhanced Spin-Dependent Tunneling Magnetoresistance In Magnetite Films Coated By Polystyrene, Wendong Wang, Leszek Malkinski, Jinke Tang Jan 2007

Enhanced Spin-Dependent Tunneling Magnetoresistance In Magnetite Films Coated By Polystyrene, Wendong Wang, Leszek Malkinski, Jinke Tang

Physics Faculty Publications

Hematite films were deposited by magnetron sputtering. A phase transformation from hematite to magnetite occurred when polystyrene (PS) coated hematite films were annealed above 200 °C in hydrogen flow. Giant negative magnetoresistance (MR) was observed with the best MR ratio of over 8% (at room temperature and in a field of 5.5 T) found in samples annealed at 230 °C. The temperature dependence of the resistivity is characteristic of intergranular tunneling. After the PS layer was removed and the films annealed again at 230 °C in hydrogen flow, the resistivity increased by about one order of magnitude and the MR …

Go to article

Microwave Absorption Of Patterned Arrays Of Nanosized Magnetic Stripes With Different Aspect Ratios, Leszek M. Malkinski, Minghui Yu, Andriy Y. Voyk, Donald J. Scherer Ii, Leonard Spinu, Weillie Zhou, Scott Whittenburg, Zachary Davis, Jin-Seung Jung Jan 2007

Microwave Absorption Of Patterned Arrays Of Nanosized Magnetic Stripes With Different Aspect Ratios, Leszek M. Malkinski, Minghui Yu, Andriy Y. Voyk, Donald J. Scherer Ii, Leonard Spinu, Weillie Zhou, Scott Whittenburg, Zachary Davis, Jin-Seung Jung

Physics 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 100 nm, a width of 300 nm, and different lengths ranging from 300 nm to 100 μm. The stripes are separated by a distance of 1 μm. Magnetization hysteresis loops were measured using a superconducting quantum interference device susceptometer. Microwave absorption at 9.8 GHz 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 …

Go to article

Quantitative Method For Measurement Of The Goos-Hanchen Effect Based On Source Divergence Considerations, Jeffrey F. Gray, Ashok Puri Jan 2007

Quantitative Method For Measurement Of The Goos-Hanchen Effect Based On Source Divergence Considerations, Jeffrey F. Gray, Ashok Puri

Physics Faculty Publications

In this paper we report on a method for quantitative measurement and characterization of the Goos-Hanchen effect based upon the real world performance of optical sources. A numerical model of a nonideal plane wave is developed in terms of uniform divergence properties. This model is applied to the Goos-Hanchen shift equations to determine beam shift displacement characteristics, which provides quantitative estimates of finite shifts near critical angle. As a potential technique for carrying out a meaningful comparison with experiments, a classical method of edge detection is discussed. To this end a line spread Green’s function is defined which can be …

Go to article

Dynamic And Temperature Effects In Toggle Magnetic Random Access Memory, Dorin Cimpoesu, Alexandru Stancu, Leonard Spinu Jan 2007

Dynamic And Temperature Effects In Toggle Magnetic Random Access Memory, Dorin Cimpoesu, Alexandru Stancu, Leonard Spinu

Physics Faculty Publications

In this paper we have studied the dynamic switching in magnetic random access memory (MRAM) and its dependence on thermal effects due to a finite temperature. The model is based on the Landau-Lifshitz-Gilbert equation and the stochastic Landau-Lifshitz-Gilbert equation which are numerically integrated. The magnetic layers are assumed to be ellipsoid shaped with each magnetic layer single domain. In addition, we have taken into account the uniaxial intrinsic anisotropy. Simulations were performed for both balanced and nonbalanced synthetic antiferromagnetic elements. The switching properties are discussed as a function of applied field pulses’ length and shape. In this paper we present …

Go to article

Physics Of Complex Transverse Susceptibility Of Magnetic Particulate Systems, Dorin Cimpoesu, Alexandru Stancu, Leonard Spinu Jan 2007

Physics Of Complex Transverse Susceptibility Of Magnetic Particulate Systems, Dorin Cimpoesu, Alexandru Stancu, Leonard Spinu

Physics Faculty Publications

Complex transverse susceptibility is a recent proposed method for the determination of anisotropy and volume distributions in particulate magnetic media. So far, only thermal fluctuations and rate-dependent damped dynamics of the magnetic moment have been identified as reasons for the existence of the imaginary transverse susceptibility. In this paper, we apply a more general approach to derive the complex transverse susceptibility, and we show that the hysteresis phenomenon is the most general concept behind the existence of complex transverse susceptibility. In this paper, the physical origins of the imaginary part of transverse susceptibility are analyzed: rate-independent hysteresis, viscous-type rate-dependent hysteresis, …

Go to article