AVS 53rd International Symposium
    Magnetic Interfaces and Nanostructures Wednesday Sessions
       Session MI-WeA

Paper MI-WeA7
The Role of Interfacial Moments in High TMR MgO-based Structures

Wednesday, November 15, 2006, 4:00 pm, Room 2006

Session: Exchange Bias & TMR
Presenter: E. Negusse, Montana State University -- Bozeman
Authors: E. Negusse, Montana State University -- Bozeman
A. Lussier, Montana State University -- Bozeman
J. Dvorak, Montana State University -- Bozeman
Y.U. Idzerda, Montana State University -- Bozeman
S.R. Shinde, Canon-Anelva, Corporation
Y. Nagamine, Canon-Anelva, Corporation
S. Furukawa, Canon-Anelva, Corporation
K. Tsunekawa, Canon-Anelva, Corporation
Correspondent: Click to Email
The large tunneling magnetoresistance (TMR) reported in MgO based magnetic tunneling junctions (MTJs) has attracted a great deal of attention for practical applications in spin-based electronic devices such as read-heads and nonvolatile memory.@footnote 1@ Recently it has been shown that adding boron to the cobalt-iron alloy electrodes created room temperature TMR of 230% by making the electrodes more amorphous and resulting in MgO barriers with good crystallinity.@footnote 2@ We used x-ray resonant magnetic scattering (XRMS), a nondestructive, element-specific and interface sensitive probe, to measure the effect of boron addition and annealing on the chemical and magnetic properties of the buried electrode-MgO interface. The specular and diffuse (interface-sensitive) scattered circularly polarized x-rays can be used to characterize the magnetic response of the moments at the interface compared to the entire film. The samples studied were 18 Å MgO films grown on 30 Å Co@Sub 70@Fe@Sub 30@ and Co@Sub 60@Fe@Sub 20@B@Sub 20@ electrodes using a UHV sputtering system (ANELVA C-7100). Our measurements showed that adding boron increased the squareness of the hysteresis loop and resulted in a significant decrease of the coercive field from 36 Oe to 5 Oe. Annealing (2 hours in an 8 kOe applied field at 360 °C) increased the grain size by 14% resulting in a slight increase in H@sub C@ for the boron containing electrode. We find that the interfacial moments for the more amorphous films behave identically to the bulk and may be the source of the increased TMR values. @FootnoteText@ @footnote 1@ S. S. P. Parkin, et al, Nat. Mater. 3, 862 (2004); S. Yuasa, et al., Nat. Mater. 3, 868 (2004).@footnote 2@ D. D. Djayaprawira, et al, Appl. Phys. Lett. 86, 092502 (2005).