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Title: Chemical and magnetic interface properties of tunnel junctionswith co2mnsi/co2fesi multilayer electrode showing large tunnelingmagnetoresistance

Abstract

Transport, as well as chemical and magnetic interface properties of two kinds of magnetic tunnel junctions (MTJs) with Co{sub 2}FeSi electrode, Al-O barrier, and Co-Fe counter electrode, are investigated. For junctions with Co{sub 2}FeSi single-layer electrodes, a tunnel magnetoresistance of up to 52% is found after optimal annealing for an optimal Al thickness of 1.5 nm, whereas the room temperature bulk magnetization of the Co{sub 2}FeSi film reaches only 75% of the expected value. By using a [Co{sub 2}MnSi/Co{sub 2}FeSi]{sub x10} multilayer electrode, the magnetoresistance can be increased to 114%, corresponding to a large spin polarization of 0.74, and the full bulk magnetization is reached. For Al thickness smaller than 1 nm, the TMR of both kinds of MTJs decreases rapidly to zero. On the other hand, for 2- to 3-nm-thick Al, the TMR decreases only slowly. The Al thickness dependence of the TMR is directly correlated to the element-specific magnetic moments of Fe and Co at the Co{sub 2}FeSi/Al-O interface for all Al thickness. Especially, for optimal Al thickness and annealing, the interfacial Fe moment of the single-layer electrode is about 20% smaller than for the multilayer electrode, indicating smaller atomic disorder at the barrier interface for the lattermore » MTJ.« less

Authors:
; ; ; ; ; ; ;
Publication Date:
Research Org.:
COLLABORATION - Department of Physics,Bielefeld University,D- 33501 Bielefeld, Germany
OSTI Identifier:
927323
Report Number(s):
LBNL-62705
TRN: US0803179
DOE Contract Number:
DE-AC02-05CH11231
Resource Type:
Conference
Resource Relation:
Conference: 10th Joint MMM/Intermag Conference, Baltimore,MD, January 7-11, 2007
Country of Publication:
United States
Language:
English
Subject:
75; ANNEALING; ELECTRODES; MAGNETIC MOMENTS; MAGNETIZATION; MAGNETORESISTANCE; POLARIZATION; SPIN; THICKNESS; TRANSPORT; TUNNELING; advanced light source als

Citation Formats

Schmalhorst, J., Ebke, D., Sacher, M.D., Liu, N., Thomas, A., Reiss, G., Hutten, A., and Arenholz, E.. Chemical and magnetic interface properties of tunnel junctionswith co2mnsi/co2fesi multilayer electrode showing large tunnelingmagnetoresistance. United States: N. p., 2007. Web.
Schmalhorst, J., Ebke, D., Sacher, M.D., Liu, N., Thomas, A., Reiss, G., Hutten, A., & Arenholz, E.. Chemical and magnetic interface properties of tunnel junctionswith co2mnsi/co2fesi multilayer electrode showing large tunnelingmagnetoresistance. United States.
Schmalhorst, J., Ebke, D., Sacher, M.D., Liu, N., Thomas, A., Reiss, G., Hutten, A., and Arenholz, E.. Mon . "Chemical and magnetic interface properties of tunnel junctionswith co2mnsi/co2fesi multilayer electrode showing large tunnelingmagnetoresistance". United States. doi:. https://www.osti.gov/servlets/purl/927323.
@article{osti_927323,
title = {Chemical and magnetic interface properties of tunnel junctionswith co2mnsi/co2fesi multilayer electrode showing large tunnelingmagnetoresistance},
author = {Schmalhorst, J. and Ebke, D. and Sacher, M.D. and Liu, N. and Thomas, A. and Reiss, G. and Hutten, A. and Arenholz, E.},
abstractNote = {Transport, as well as chemical and magnetic interface properties of two kinds of magnetic tunnel junctions (MTJs) with Co{sub 2}FeSi electrode, Al-O barrier, and Co-Fe counter electrode, are investigated. For junctions with Co{sub 2}FeSi single-layer electrodes, a tunnel magnetoresistance of up to 52% is found after optimal annealing for an optimal Al thickness of 1.5 nm, whereas the room temperature bulk magnetization of the Co{sub 2}FeSi film reaches only 75% of the expected value. By using a [Co{sub 2}MnSi/Co{sub 2}FeSi]{sub x10} multilayer electrode, the magnetoresistance can be increased to 114%, corresponding to a large spin polarization of 0.74, and the full bulk magnetization is reached. For Al thickness smaller than 1 nm, the TMR of both kinds of MTJs decreases rapidly to zero. On the other hand, for 2- to 3-nm-thick Al, the TMR decreases only slowly. The Al thickness dependence of the TMR is directly correlated to the element-specific magnetic moments of Fe and Co at the Co{sub 2}FeSi/Al-O interface for all Al thickness. Especially, for optimal Al thickness and annealing, the interfacial Fe moment of the single-layer electrode is about 20% smaller than for the multilayer electrode, indicating smaller atomic disorder at the barrier interface for the latter MTJ.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Mon Jan 01 00:00:00 EST 2007},
month = {Mon Jan 01 00:00:00 EST 2007}
}

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  • No abstract prepared.
  • The knowledge of chemical and magnetic conditions at the Co{sub 40}Fe{sub 40}B{sub 20}/MgO interface is important to interpret the strong annealing temperature dependence of tunnel magnetoresistance of Co-Fe-B/MgO/Co-Fe-B magnetic tunnel junctions, which increases with annealing temperature from 20% after annealing at 200 C up to a maximum value of 112% after annealing at 350 C. While the well defined nearest neighbor ordering indicating crystallinity of the MgO barrier does not change by the annealing, a small amount of interfacial Fe-O at the lower Co-Fe-B/MgO interface is found in the as grown samples, which is completely reduced after annealing at 275more » C. This is accompanied by a simultaneous increase of the Fe magnetic moment and the tunnel magnetoresistance. However, the TMR of the MgO based junctions increases further for higher annealing temperature which can not be caused by Fe-O reduction. The occurrence of an x-ray absorption near-edge structure above the Fe and Co L-edges after annealing at 350 C indicates the recrystallization of the Co-Fe-B electrode. This is prerequisite for coherent tunneling and has been suggested to be responsible for the further increase of the TMR above 275 C. Simultaneously, the B concentration in the Co-Fe-B decreases with increasing annealing temperature, at least some of the B diffuses towards or into the MgO barrier and forms a B{sub 2}O{sub 3} oxide.« less
  • No abstract prepared.
  • The relationship between microstructure and physical behavior is especially pronounced in synthetic multilayer materials. Insight to the mechanisms responsible for changes in the mechanical properties can be investigated through a careful examination of the inherent microstructure. A dominant feature of the multilayer structure is the interface. The population of interlayer boundaries, that is interfaces, is directly controlled by the multilayer period for any given film thickness. In this paper, we will present TEM images of multilayer systems. The interface structure will be viewed in cross-section. A range of layer thicknesses should be considered as variations in the elastic modules, yieldmore » stress, and microhardness have been observed for many noble-transition metal systems over a wide range of multilayer periods, from less than 1 nm to greater than 1000 nm. In epitaxial systems, the extent of superlattice perfection (coherency effects) is closely tied with changes in physical behavior. In summation, emphasis will be placed on the structure and strain distribution from the interface, and its role in determining the mechanical properties of multilayers. 23 refs., 2 figs.« less
  • No abstract prepared.