Colossal magnetoresistance materials-based junctions with antiferromagnetic insulating barriers

We have fabricated epitaxial La0.7Sr0.3MnO3/La0.35Ca0.65MnO3/La0.7Sr0.3MnO3 trilayer magnetic tunnel junctions in order to produce high-quality interfaces through the use of an isostructural barrier layer. The barrier we have chosen (La0.35Ca0.65MnO3) is an antiferromagnetic insulator with a Neel temperature of similar to160 K. We observed junction magnetoresistances (JMRs) of up to 4% at 5 K. The large energy cost to flip a spin in an antiferromagnet preserves some degree of spin orientation during transport through the junctions. However, magnetic coupling between the electrode and the barrier inevitably suppresses the JMR. Despite the magnetic coupling, an antiferromagnetic barrier does not suppress the JMR completely. (C) 2004 American Institute of Physics.