Magnetotransport properties of ferromagnetic semiconductor GaMnAs-based superlattices
2012 (English)In: Current applied physics, ISSN 1567-1739, E-ISSN 1878-1675, Vol. 12, no SUPPL. 2, S31-S36 p.Article in journal (Refereed) Published
Two series of GaMnAs/GaAs superlattices (SSs) comprised of ferromagnetic semiconductor GaMnAs layers and non-magnetic GaAs spacers were investigated by the electronic transport measurements with an external magnetic field applied in the plane of the sample. The two SL series consisted of specimens that were structurally the same, but the GaAs spacers layers of one series were doped by Be, while in the second series the spacers were undoped. Although in field scans taken at 4 K all SLs showed a typical anisotropic magnetoresistance (MR) behavior dominated by magnetic anisotropy, similar to that normally observed in single GaMnAs ferromagnetic layers grown on GaAs (001) substrates, some of the SLs showed signatures of interaction between the GaMnAs layers in the form of broadening of the MR hysteresis. The effect of inter-layer exchange coupling (IEC) between the GaMnAs magnetic layers became clear in the MR data taken at 30 K, where the strength of the magnetic anisotropy was reduced to the level of the inter-layer interaction. Specifically, MR measurements on two of the Be-doped SLs (BD2 and BD3) exhibited conspicuously large values of resistance at zero field, along with transitions of magnetization with negative coercive fields. The observation of these features in GaMnAs/GaAs SLs indicates the presence of spontaneous antiferromagnetic (AFM) inter-layer exchange coupling (IEC) between the GaMnAs magnetic layers. The study further revealed that the IEC in the GaMnAs multilayers strongly depended on the properties of the non-magnetic GaAs spacers, such as their thickness and the density of carriers in the layers. Importantly, these IEC effects occurred on a longer range than that expected from current theoretical studies.
Place, publisher, year, edition, pages
2012. Vol. 12, no SUPPL. 2, S31-S36 p.
Ferromagnetic semiconductor, GaMnAs, Inter-layer exchange coupling, Magnetoresistance, Superlattice, Anisotropic magnetoresistance, Antiferromagnetics, Coercive field, Electronic transport measurements, External magnetic field, Ferromagnetic layers, GaAs, GaAs(001), In-field, Interlayer exchange coupling, Magnetic layers, Magneto transport properties, Nonmagnetics, Theoretical study, Zero fields, Antiferromagnetism, Exchange coupling, Ferromagnetic materials, Ferromagnetism, Gallium arsenide, Magnetic anisotropy, Magnetic multilayers, Semiconducting gallium, Semiconductor superlattices, Superlattices, Gallium alloys
Condensed Matter Physics
IdentifiersURN: urn:nbn:se:kth:diva-105572DOI: 10.1016/j.cap.2012.02.014ISI: 000310941500007OAI: oai:DiVA.org:kth-105572DiVA: diva2:574475
QC 201212172012-12-052012-11-222012-12-17Bibliographically approved