Spin-dependent tunneling through high-k LaAlO3

Vincent Garcia (1) , M Bibes (2) , Jl Maurice , E Jacquet (3) , K Bouzehouane (2) , Jp Contour , Alain Barthélémy

1 INSP - Institut des Nanosciences de Paris
2 Laboratoire Albert Fert (ex-UMPhy Unité mixte de physique CNRS/Thales)
3 Groupe de Biophysique

We report on the use of the LaAlO3 (LAO) high-k dielectric as a tunnel barrier in magnetic tunnel junctions. From tunnel magnetoresistance (TMR) measurements on epitaxial La2/3Sr1/3MnO3/LAO/La2/3Sr1/3MnO3 junctions, we estimate a spin polarization of 77% at low temperature for the La2/3Sr1/3MnO3/LAO interface. Remarkably, the TMR of La2/3Sr1/3MnO3/LAO/Co junctions at low bias is negative, evidencing a negative spin polarization of Co at the interface with LAO, and its bias dependence is very similar to that of La2/3Sr1/3MnO3/SrTiO3/Co junctions. We discuss possible reasons for this behavior. (c) 2005 American Institute of Physics.

Domaines: Matière Condensée [cond-mat]

Vincent Garcia, M Bibes, Jl Maurice, E Jacquet, K Bouzehouane, et al.. Spin-dependent tunneling through high-k LaAlO3. Applied Physics Letters, 2005, 87 (21), pp.212501. ⟨10.1063/1.2132526⟩. ⟨hal-01293056⟩