Spin dependent transport in Co nano-scale tunnel junctions
2002 (English)Licentiate thesis, comprehensive summary (Other scientific)
Ferromagnetic tunnel junctionshave been fabricated, measured and theoretically described. Anoverview of the Julliere model, and Slonczewski's model todescribe the resistance change due to di®erent orientationof the magnetization between the magnetic electrodes(magnetoresistance) is given. Then a double-junctionconfiguration is theoretically analyzed in the sense of localspin accumulation related to the length an electron can travelbefore relaxing its spin. The analysis shows that thee®ect of spin accumulation contributes with a very smallor negligiblechange of the magnetoresistance for adouble-junction with large resistive barriers, and biased witha small voltage compared with a simple two-resistors-in-seriesmodel. Single-, triple-, and five- junction arrays werefabricated and measured. In order to analyze the spinaccumulation e®ect a double-junction with three terminalswas fabricated and measured to enable measurement of eachjunction of the double junction individually. Thedouble-junction configuration did not show any additionalmagnetoresistance over the two-junctions-in-series value at lowvoltage bias. However, the magnetoresistance of adouble-junction exhibited a weaker dependence on the biasvoltage than that expected for two junctions in series.
Place, publisher, year, edition, pages
Stockholm: Fysik , 2002. , 53 p.
Trita-FYS, ISSN 0280-316X ; 2001:11
IdentifiersURN: urn:nbn:se:kth:diva-1381ISBN: 91-7283-236-3OAI: oai:DiVA.org:kth-1381DiVA: diva2:7233
NR 201408052002-01-232002-01-23Bibliographically approved