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.