Temperature dependence of the interfacial spin polarization of La2/3Sr1/3MnO3 -: art. no. 052403

We have measured the tunneling magnetoresistance (TMR) of magnetic tunnel junctions based on La2/3Sr1/3MnO3 and various barrier materials (SrTiO3, TiO2, LaAlO3). The interfacial spin polarization of La2/3Sr1/3MnO3 is derived from the TMR and we find that its temperature dependence strongly resembles that of the bulk magnetization and hardly depends on the barrier material. However, the apparent Curie temperature is some 60 K lower. This dependence contrasts with that of the spin polarization of a free La2/3Sr1/3MnO3 surface, as probed by spin-polarized photoemission [J.-H. Park , Phys. Rev. Lett. 81, 1953 (1998)], thus evidencing that surfaces and interfaces have very different properties in manganites.