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Magnetotransport in magnetic nanostr...

Panchula, Alex F.

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Magnetotransport in magnetic nanostructures.

Record Type:	Electronic resources : Monograph/item
Title/Author:	Magnetotransport in magnetic nanostructures./
Author:	Panchula, Alex F.
Description:	137 p.
Notes:	Source: Dissertation Abstracts International, Volume: 64-11, Section: B, page: 5575.
Contained By:	Dissertation Abstracts International64-11B.
Subject:	Physics, Condensed Matter. -
Online resource:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3111776

Magnetotransport in magnetic nanostructures.
Panchula, Alex F.

Magnetotransport in magnetic nanostructures. - 137 p.

Source: Dissertation Abstracts International, Volume: 64-11, Section: B, page: 5575.

Thesis (Ph.D.)--Stanford University, 2004.

The unifying theme of this dissertation is the exploration of novel magnetic thin film materials to improve our understanding of spin-dependent transport in such materials, especially with regard to their use in the nascent field of spin based devices. Such devices, which rely on controlling the electron's spin rather than its charge as in conventional micro-electronics, may be important for applications in sensing, memory and computation. This dissertation covers research performed at the IBM Almaden Research Center between 2000 and 2003.Subjects--Topical Terms:

1018743
Physics, Condensed Matter.

Magnetotransport in magnetic nanostructures.
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008 130614s2004 eng d
035 $a (UnM)AAI3111776
035 $a AAI3111776
040 $a UnM $c UnM
100 1 $a Panchula, Alex F. $3 1952800
245 1 0 $a Magnetotransport in magnetic nanostructures.
300 $a 137 p.
500 $a Source: Dissertation Abstracts International, Volume: 64-11, Section: B, page: 5575.
500 $a Adviser: Stuart S. P. Parkin.
502 $a Thesis (Ph.D.)--Stanford University, 2004.
520 $a The unifying theme of this dissertation is the exploration of novel magnetic thin film materials to improve our understanding of spin-dependent transport in such materials, especially with regard to their use in the nascent field of spin based devices. Such devices, which rely on controlling the electron's spin rather than its charge as in conventional micro-electronics, may be important for applications in sensing, memory and computation. This dissertation covers research performed at the IBM Almaden Research Center between 2000 and 2003.
520 $a One class of spin-based devices are magnetic tunnel junctions (MTJs), which display large changes in resistance in small magnetic fields. This tunneling magnetoresistance (TMR) is derived from changes in the relative alignment of the magnetic moments of thin ferromagnetic layers which are separated by thin insulating layers. The tunneling current spin polarization (TSP) determines the magnitude of the TMR. For typical transition-metal ferromagnets and their alloys the TSP is &sim;50% although it is anticipated that half-metals should display nearly 100%.
520 $a Confirming theoretical predictions, MTJs with electrodes of magnetite and a conventional ferromagnet such as a CoFe alloy, display an inverted TMR, consistent with negatively spin polarized magnetite electrodes. However, the magnitude of TSP of -48% at low temperatures, is not much larger than that exhibited by conventional 3d transition metal ferromagnets. At high temperatures, transport through the MTJ is dominated by tunneling across the alumina tunnel barrier, while at low temperatures the bulk properties of the magnetite dominates at low bias voltage. Another class of half-metals, the semi-heuslers exhibit low TSP, most likely due to surface disorder and, as revealed in this work, the possible formation of MnSb. The MnSb alloys studied in MTJs are found to behave as typical ferromagnets with a small positive TMR.
520 $a Also considered are MTJs whose barriers are comprised of the wide band-gap semiconductors, ZnSe and Cr2O3. These low barrier height materials show typical tunneling behavior, although the TMR is lower than found for wide-gap insulators. Finally, the development of a high precision SQUID based voltmeter for application to low resistance devices with the current perpendicular to the plane of the materials is outlined.
590 $a School code: 0212.
650 4 $a Physics, Condensed Matter. $3 1018743
650 4 $a Engineering, Materials Science. $3 1017759
650 4 $a Physics, Electricity and Magnetism. $3 1019535
690 $a 0611
690 $a 0794
690 $a 0607
710 2 0 $a Stanford University. $3 754827
773 0 $t Dissertation Abstracts International $g 64-11B.
790 1 0 $a Parkin, Stuart S. P., $e advisor
790 $a 0212
791 $a Ph.D.
792 $a 2004
856 4 0 $u http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3111776