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Switching characteristics and magnetoresistance of Co-based multilayered perpendicular magnetic tunnel junctions

Published online by Cambridge University Press:  31 January 2011

Zeenath Reddy Tadisina ,
Anusha Natarajarathinam  and
Subhadra Gupta
Zeenath Reddy Tadisina
Affiliation:
ztadisina@crimson.ua.edu, University of Alabama, MINT Center, Tuscaloosa, Alabama, United States
Anusha Natarajarathinam
Affiliation:
anush.nat@gmail.com, University of Alabama, MINT Center, Tuscaloosa, Alabama, United States
Subhadra Gupta
Affiliation:
sgupta@eng.ua.edu, The University of Alabama, Metallurgical and Materials Engineering, A102 Bevill, MTE Dept, University of Alabama Box 870202,, Tuscaloosa, Alabama, 35487-0202, United States
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Abstract

Perpendicularly magnetized magnetic tunnel junctions (pMTJ) using Co based multilayers as free and reference layers have been optimized for perpendicular magnetic anisotropy (PMA) and high tunneling magnetoresistance (TMR). The effect of seed layers, Co thickness and Co/Ni thickness ratio on the anisotropy of these multilayer films has been studied. Intermixing of these multilayers was analyzed by local electrode atom probe (LEAP). The effect of Co thickness, Pd thickness and number of Co/Pd bilayers on the anisotropy and coercivity of the [Co/Pd]n multilayer films have been studied for both free and reference layers. The magnetic behavior of these PMA systems was studied by alternating gradient magnetometer. CoFeB/MgO/CoFeB trilayers sandwiched between the PMA multilayer material systems were studied. The transport properties of the patterned MTJ stacks were measured by PPMS from 10K to 400 K. A maximum TMR of 10% at 10K (5-10% at 300 K) was obtained for these perpendicular MTJ’s (pMTJ), regardless of whether they were magnetically annealed for MgO-CoFeB crystallization or not, indicating that the fcc-bcc-fcc transitions from the fcc multilayers to the bcc CoFeB/MgO/CoFeB do not promote the “giant MgO TMR effect” caused by symmetry filtering.

Keywords

spintroniclayeredmagnetoresistance (transport)
Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 1198: Symposium E – Advanced Materials for Half-Metallic and Organic Spintronics , 2009 , 1198-E02-08
Copyright
Copyright © Materials Research Society 2010

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