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Your search keyword '"Gregg, J. F."' showing total 98 results
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98 results on '"Gregg, J. F."'

1. Magnonic crystal based forced dominant wavenumber selection in a spin-wave active ring

Author

Karenowska, A. D., Chumak, A. V., Serga, A. A., Gregg, J. F., and Hillebrands, B.

Subjects
Condensed Matter - Other Condensed Matter
Abstract

Spontaneous excitation of the dominant mode in a spin-wave active ring -- a self-exciting positive-feedback system incorporating a spin-wave transmission structure -- occurs at a certain threshold value of external gain. In general, the wavenumber of the dominant mode is extremely sensitive to the properties and environment of the spin-wave transmission medium, and is almost impossible to predict. In this letter, we report on a backward volume magnetostatic spin-wave active ring system incorporating a magnonic crystal. When mode enhancement conditions -- readily predicted by a theoretical model -- are satisfied, the ring geometry permits highly robust and consistent forced dominant wavenumber selection., Comment: 4 pages, 3 figures

Published
2009
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2. Circuit Theory for the Electrically Declined

Author

Gregg, J. F., Thornton, M. J., Beig, R., editor, Ehlers, J., editor, Frisch, U., editor, Hepp, K., editor, Hillebrandt, W., editor, Imboden, D., editor, Jaffe, R. L., editor, Kippenhahn, R., editor, Lipowsky, R., editor, Löhneysen, H. V., editor, Ojima, I., editor, Weidenmüller, H. A., editor, Wess, J., editor, Zittartz, J., editor, Ziese, Michael, editor, and Thornton, Martin J., editor

Published
2001
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3. Introduction to Spin Electronics

Author

Gregg, J. F., Beig, R., editor, Ehlers, J., editor, Frisch, U., editor, Hepp, K., editor, Hillebrandt, W., editor, Imboden, D., editor, Jaffe, R. L., editor, Kippenhahn, R., editor, Lipowsky, R., editor, Löhneysen, H. V., editor, Ojima, I., editor, Weidenmüller, H. A., editor, Wess, J., editor, Zittartz, J., editor, Ziese, Michael, editor, and Thornton, Martin J., editor

Published
2001
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14. Evidence for electrical spin tunnel injection into silicon.

Author

Dennis, C. L., Gregg, J. F., Ensell, G. J., and Thompson, S. M.

Subjects
*QUANTUM tunneling, *ELECTRON transport, *MAGNETIC fields, *POLARIZATION (Electricity), *SEMICONDUCTORS
Abstract

Electrical spin injection into silicon was studied in a ferromagnet/insulator/silicon/insulator/ferromagnet structure, where the insulator is Si3N4. Si3N4 barriers conduct by hopping conduction at low voltages, but switch to Fowler-Nordheim tunneling at high voltages. In the Fowler-Nordheim tunneling regime a magnetic field dependence of the output current consistent with spin dependent transport through the silicon is observed; in the hopping conduction regime reduced magnetic field dependence of the output current is observed. This voltage dependence of the magnetic sensitivity strongly supports the existence of spin injection into silicon. After correction for Lorentz magnetoresistance, the magnitude of this signal is 4.1%±0.5% (12%±5%) for p-type (n-type) Si. [ABSTRACT FROM AUTHOR]

Published
2006
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16. Spin polarized electronic reflections at metal–oxide interfaces: A technique for characterizing tunneling barriers in magnetic random access memory devices.

Author

Ounadjela, K., Da Costa, V., Iovan, A., Dimopoulos, T., Dahmani, F., Mahenthiran, D., Dieny, B., Allen, W., and Gregg, J. F.

Subjects
QUANTUM tunneling, RANDOM access memory
Abstract

One of the most critical steps in the realization of high quality tunneling devices is the fabrication of ultrathin oxide layers. This article describes a powerful technique for controlling the oxidation of ultrathin metallic layers. The technique consists of depositing the metallic layer to be oxidized on top of the soft magnetic layer of a bottom spin valve. The oxidation kinetics are then monitored by measuring the current in plane sheet resistance and magnetoresistance. The technique relies on the extreme sensitivity of the magnetoresistance on the degree of specular reflection at the soft magnetic layer/oxide interface. [ABSTRACT FROM AUTHOR]

Published
2002
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17. High-sensitivity ultrasonic interferometer for the detection of magnetic phase transitions.

Author

Huan, C. H. A., Gregg, J. F., Wells, M. R., Briggs, G. A. D., and Wolf, W. P.

Subjects
*ACOUSTIC surface waves, *INTERFEROMETRY, *MAGNETISM, *POLARIZATION (Electricity)
Abstract

Presents a method for the detection of magnetic phase transitions using acoustic waves with electrical interferometry. Information on ultrasonic interferometry; Application of the technique; Implications on the disparity between the traces of acoustic polarization.

Published
1987
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18. Jitterbug spin channel mixing in heterogeneous giant magnetoresistive material.

Author

Gregg, J. F., Allen, W., Thompson, S. M., Watson, M. L., and Gehring, G. A.

Subjects
*MAGNETICS, *SPIN waves, *MAGNETORESISTANCE, *MAGNETIC materials
Abstract

Presents a study that described a mechanism which considers the effect of small magnetic properties on the spin diffusion length in a granular giant magnetoresistive (GMR) material. Classes of magnetic clusters in a granular GMR material; Details of the depolarization mechanism; Information on a numerical simulation of the jitterbug effect of the GMR.

Published
1996
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19. Relaxation dynamics of metastable antiferromagnetic states.

Author

Gregg, J. F., Kob, W., Lord, J. S., Morris, I. D., Pfeffer, J. Z., Schilling, R., Wells, M. R., and Wolf, W. P.

Subjects
*TRANSITION metals, *ISING model, *ANTIFERROMAGNETISM
Abstract

Investigates the relaxation dynamics of an order-order transition in an Ising antiferromagnet. Nucleation in magnetic systems through the Monte Carlo simulation; Application of the ultrasonic interferometry to the metamagnet dysprosium aluminum garnet; Values of the order parameter for time reversed states.

Published
1990
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20. Structural characterization of epitaxial Co–Ag.

Author

Azizi, A., El Chahal, L., Ounadjela, K., Deville, J. P., Thompson, S. M., and Gregg, J. F.

Subjects
TEMPERATURE, COBALT, MAGNETORESISTANCE
Abstract

Deals with a study which investigated the effect that growth temperature has on the shape, size, location, and segregation of the magnetic cobalt grains and the morphology of the surface. Information on giant magnetoresistance; Methodology of the study; Results and discussion.

Published
1996
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21. Giant magnetoresistance and induced exchange anisotropy in mechanically alloyed Co30Ag70.

Author

Ounadjela, K., Herr, A., Poinsot, R., Coey, J. M. D., Fagan, A., Staddon, C. R., Daniel, D., Gregg, J. F., Thompson, S. M., O’Grady, K., and Grieves, S.

Subjects
MAGNETORESISTANCE, MAGNETIC alloys
Abstract

Presents information on a study that observed giant magnetoresistance in bulk mechanically alloyed Co[sub30]Ag[sub70]. Experimental procedure; Experimental results and discussion; Conclusion.

Published
1994
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30. Magnetoresistance through a single nickel atom

Author

Viret, M., primary, Berger, S., additional, Gabureac, M., additional, Ott, F., additional, Olligs, D., additional, Petej, I., additional, Gregg, J. F., additional, Fermon, C., additional, Francinet, G., additional, and Goff, G. Le, additional

Published
2002
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31. The defining length scales of mesomagnetism: a review

Author

Dennis, C L, primary, Borges, R P, additional, Buda, L D, additional, Ebels, U, additional, Gregg, J F, additional, Hehn, M, additional, Jouguelet, E, additional, Ounadjela, K, additional, Petej, I, additional, Prejbeanu, I L, additional, and Thornton, M J, additional

Published
2002
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33. Spin Polarization of Injected Electrons

Author

Egelhoff, W. F., primary, Stiles, M. D., additional, Pappas, D. P., additional, Pierce, D. T., additional, Byers, J. M., additional, Johnson, M. B., additional, Jonker, B. T., additional, Alvarado, S. F., additional, Gregg, J. F., additional, Bland, J. A. C., additional, and Buhrman, R. A., additional

Published
2002
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35. Circuit Theory for the Electrically Declined.

Author

Beig, R., Ehlers, J., Frisch, U., Hepp, K., Hillebrandt, W., Imboden, D., Jaffe, R. L., Kippenhahn, R., Lipowsky, R., Löhneysen, H. V., Ojima, I., Weidenmüller, H. A., Wess, J., Zittartz, J., Ziese, Michael, Thornton, Martin J., Gregg, J. F., and Thornton, M. J.

Abstract

Such is the sophistication of many contemporary University Physics Courses that their followers are at ease with the finer details of the Dirac equation and have no difficulty in thinking in a many-dimensioned Hilbert-space: however they are often less confident when faced with knowing which end of a soldering iron gets hot. Spin Electronics is above all a practical science which ultimately promises to implement a new and revolutionary technology in a form which will ultimately impact everyday existence. Card-carrying theoretical physicists doubtless have their part to play in this new and exciting field, but for the rapid and successful development of this science, the importance of practical knowledge and experimental dexterity is paramount. Those who would claim proficiency as Spin Electronicians must, above all, be capable of the simple, basic skills with which every TV repair engineer is acquainted. To those devotees of Spin Electronics whose degree courses have left you electrically deprived, this chapter is dedicated to you. Evidently, in the few pages available, only the surface of this topic may be scratched, but at least the basics can be laid, topics of major confusion like transistors and transformers can be treated and signposts pointed to further study. [ABSTRACT FROM AUTHOR]

Published
2001
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36. Introduction to Spin Electronics.

Author

Beig, R., Ehlers, J., Frisch, U., Hepp, K., Hillebrandt, W., Imboden, D., Jaffe, R. L., Kippenhahn, R., Lipowsky, R., Löhneysen, H. V., Ojima, I., Weidenmüller, H. A., Wess, J., Zittartz, J., Ziese, Michael, Thornton, Martin J., and Gregg, J. F.

Abstract

The driving force behind Spin Electronics is neatly summarized in J. M. D. Coey's incisive observation [1] that "Conventional Electronics has ignored the spin of the electron". In every hi-fi and radio set, 50% of the conducting electrons tend to be spin-up and the remainder are spin down (where up and down relate to some locally induced quantisation axis in the relevant wires and devices). Yet, although electron spin was known about for most of the 20th Century, no technical use is made of this fact. [ABSTRACT FROM AUTHOR]

Published
2001
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46. Silicon spin diffusion transistor: materials, physics and device characteristics.

Author

Dennis, C. L., Tiusan, C. V., Gregg, J. F., Ensell, G. J., and Thompson, S. M.

Subjects
SPINTRONICS, ELECTRIC equipment, MAGNETIC fields, MAGNETIC materials, MICROELECTRONICS, NANOTECHNOLOGY
Abstract

The article focuses on devices related to the field of spin electronics. Everyday electronic devices manipulate carriers solely based on their charge, either positive or negative. Their operation ignores the fact that those carriers also have a spin, either spin up or spin down. Spin electronics aims to remedy this deficiency by manipulating the spin as well as the charge of the carrier in nano-scale devices. Spintronics goes beyond the simple use of magnetic fields to alter the movement of charge. Instead, spintronics determines and/or senses the spin orientation of the carriers by incorporating magnetic materials into conventional devices.

Published
2005
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49. Spin electronics—a review

Author

Gregg, J F, Petej, I, Jouguelet, E, and Dennis, C

Abstract

An overview is given of the state of the art in spin electronics. The technical basis is reviewed and simple ideas of giant magnetoresistance discussed. The connection between spin electronics and mesomagnetism is explored. Three-terminal spin-electronic devices are introduced of various types including hot carrier and hybrid spin/semiconductor devices. Spin-tunnel devices are examined and single spin electronics is also treated. The paper concludes with an outlook on future prospects in this field. Hence you long legg'd spinners, hence. William Shakespeare

Published
2002

50. Kapitza resistance in HoVO4 below 100 mK

Author

Jacquinot, J. F., Gregg, J. F., Roinel, Y., Fermon, C., and Bouffard, V.

Abstract

The warmup rate of the165Ho-enhanced nuclear spins in a HoVO4 single crystal in contact with dilute3He is shown to be dominated by the Kapitza resistanceRK at low bath temperature (Tb<100 mK). This result is obtained from an analysis of the NMR signal during the warmup, following a demagnetization which cools the sample to a temperature of about 5 mK. The temperature variation ofRK (?Tb</-3) is consistent with the acoustic mismatch model, but the magnitude is 40 times smaller than the theoretical predictions for a solid-liquid interface. The spin-lattice relaxation is also estimated, and found to be in agreement with the results of other authors.

Published
1986
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