Room-temperature spintronic effects in Alq3 -based hybrid devices
2008 (English)In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, Vol. 78, no 11Article in journal (Refereed) Published
We report on efficient spin polarized injection and transport in long (102 nm) channels of Alq3 organic semiconductor. We employ vertical spin valve devices with a direct interface between the bottom manganite electrode and Alq3, while the top-electrode geometry consists of an insulating tunnel barrier placed between the "soft" organic semiconductor and the top Co electrode. This solution reduces the ubiquitous problem of the so-called ill-defined layer caused by metal penetration, which extends into the organic layer up to distances of about 50-100 nm and prevents the realization of devices with well-defined geometry. For our devices the thickness is defined with an accuracy of about 2.5 nm, which is near the Alq3 molecular size. We demonstrate efficient spin injection at both interfaces in devices with 100- and 200-nm-thick channels. We solve one of the most controversial problems of organic spintronics: the temperature limitations for spin transport in Alq3 -based devices. We clarify this issue by achieving room-temperature spin valve operation through the improvement of spin injection properties of both ferromagnetic/ Alq3 interfaces. In addition, we discuss the nature of the inverse sign of the spin valve effect in such devices proposing a mechanism for spin transport. © 2008 The American Physical Society.
Place, publisher, year, edition, pages
2008. Vol. 78, no 11
Engineering and Technology
IdentifiersURN: urn:nbn:se:liu:diva-50165DOI: 10.1103/PhysRevB.78.115203OAI: oai:DiVA.org:liu-50165DiVA: diva2:271061