Phys. Rev. Lett. 108, 186802 (2012 )

Oxides play an important role in spintronics, as they are used for the barriers in magnetic tunnelling junctions. However, as this class of materials includes ferroelectrics, ferromagnets and multiferroics, we could in principle envisage all-oxide-based spintronics devices. Before such a goal can be achieved it is essential to achieve injection of spin-polarized electrons directly into an oxide layer. LaAlO3–SrTiO3 structures are ideal systems for studying spin transport, as the electron gas formed at the interface between the two materials has been shown to have large electron mobility. Nicholas Reyren and colleagues have now observed spin injection from a ferromagnetic contact into a LaAlO3/SrTiO3 interface. They deposited the ferromagnetic electrode on top of the LaAlO3, which served as a tunnel barrier. The details of the experiments suggest a sequential tunnelling, from the electrode into localized states in the barrier, and subsequently from these states into the interface. The next step will be to improve the device design and the materials to finally obtain direct injection into the interface.