Origin of high transport spin polarization in La0.7Sr0.3MnO3: Direct evidence for minority spin states - art. no. 184433

Using the point-contact Andreev reflection technique, we have carried out a systematic study of the spin polarization in the colossal magnetoresistive manganite. La0.7Sr0.3MnO3 (LSMO). Surprisingly, we observed a significant increase in the current spin polarization with the residual resistivity. Th is counterintuitive trend can be understood as a transition from ballistic to diffusive transport in the contact. Our results strongly suggest that LS MO does have minority spin states at the Fermi Level. However, since its cu rrent spin polarization is much higher than that of the density of states, this material can mimic the behavior of a true half-metal in transport expe riments. Based on our results we call this material a transport half-metal.