Role of boron diffusion in CoFeB/MgO magnetic tunnel junctions
2015 (English)In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 91, no 8, 085311Article in journal (Refereed) Published
Several scientific issues concerning the latest generation read heads for magnetic storage devices, based on CoFeB/MgO/CoFeBmagnetic tunnel junctions (MTJs) are known to be controversial, including such fundamental questions as to the behavior and the role of B in optimizing the physical properties of these devices. Quantitatively establishing the internal structures of several such devices with different annealing conditions using hard x-ray photoelectron spectroscopy, we resolve these controversies and establish that the B diffusion is controlled by the capping Ta layer, though Ta is physically separated from the layer with B by several nanometers. While explaining this unusual phenomenon, we also provide insight into why the tunneling magnetoresistance (TMR) is optimized at an intermediate annealing temperature, relating it to B diffusion, coupled with our studies based on x-ray diffraction and magnetic studies.
Place, publisher, year, edition, pages
2015. Vol. 91, no 8, 085311
IdentifiersURN: urn:nbn:se:kth:diva-163999DOI: 10.1103/PhysRevB.91.085311ISI: 000350319200013ScopusID: 2-s2.0-84924081350OAI: oai:DiVA.org:kth-163999DiVA: diva2:810620
FunderThe Swedish Foundation for International Cooperation in Research and Higher Education (STINT)
QC 201505072015-05-072015-04-132015-05-07Bibliographically approved