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, ISSN 1098-0121, 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/CoFeB magnetic 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
Condensed Matter Physics
Research subject Physics with spec. in Atomic, Molecular and Condensed Matter Physics
IdentifiersURN: urn:nbn:se:uu:diva-247784DOI: 10.1103/PhysRevB.91.085311ISI: 000350319200013ScopusID: 2-s2.0-84924081350OAI: oai:DiVA.org:uu-247784DiVA: diva2:797426