Room-temperature spintronic effects in<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow><mml:mtext>Alq</mml:mtext></mml:mrow><mml:mn>3</mml:mn></mml:msub></mml:mrow></mml:math>-based hybrid devices

We report on efficient spin polarized injection and transport in long $({10}^{2}\text{ }\text{nm})$ channels of ${\text{Alq}}_{3}$ organic semiconductor. We employ vertical spin valve devices with a direct interface between the bottom manganite electrode and ${\text{Alq}}_{3}$, 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 ${\text{Alq}}_{3}$ 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 ${\text{Alq}}_{3}$-based devices. We clarify this issue by achieving room-temperature spin valve operation through the improvement of spin injection properties of both ferromagnetic/${\text{Alq}}_{3}$ 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.