Understanding spin dependent transport through Alq3 molecules

Molecular and organic spintronics offers the opportunity to play with chemical versatility and to bring the spin degree of freedom to electronics devices. We will show how, as a contender to commonly used inorganic materials, organic/molecular based spintronics devices can exhibit very large magnetoresistance and lead to tailored spin polarizations. First we will report on giant tunnel magnetoresistance of up to 300{\%} in a (La,Sr)MnO$_{3}$/Alq$_{3}$/Co nanometer size magnetic tunnel junctions. Samples are nanofabricated using a conductive tip AFM nanolithography process in order to circumvent problems such as inhomogeneity and strong metal diffusion. In a second part we will present a spin dependent transport model giving a new understanding of spin injection into organic materials. We will show how one could tune spin injection by molecular engineering.