Colossal magnetoresistance magnetic tunnel junctions grown by molecular-beam epitaxy.

Using molecular-beam-epitaxy growth techniques, we have synthesized ferromagnet/insulator/ferromagnet trilayer heterostructures with the "colossal" magnetoresistance material La[sub 1-x]Sr[sub x]MnO[sub 3] as the ferromagnet. These trilayer films were fabricated into magnetic tunnel junctions which exhibit magnetoresistance ΔR/R(H) of as much as 450% in 200 Oe applied field at 14 K, and which persists up to ∼250 K. In situ reflection high-energy electron diffraction (RHEED) allows us to correlate the quality of the epitaxial growth with the magnetoresistive properties. Samples which showed signs of disorder in RHEED also exhibit disorder effects in low-temperature transport and have smaller magnetoresistance which vanishes at lower temperatures. © 2000 American Institute of Physics. [ABSTRACT FROM AUTHOR]