Improved tunneling magnetoresistance at low temperature in manganite junctions grown by molecular beam epitaxy

We report resistance versus magnetic field measurements for a La 0.65 Sr 0.35 MnO 3 / SrTiO 3 / La 0.65 Sr 0.35 MnO 3 tunnel junction grown by molecular-beam epitaxy, that show a large field window of extremely high tunneling magnetoresistance (TMR) at low temperature. Scanning the in-plane applied field orientation through 360°, the TMR shows fourfold symmetry, i.e., biaxial anisotropy, aligned with the crystalline axis but not the junction geometrical long axis. The TMR reaches ∼ 1900 % at 4 K, corresponding to an interfacial spin polarization of > 95 % assuming identical interfaces. These results show that uniaxial anisotropy is not necessary for large TMR, and lay the groundwork for future improvements in TMR in manganite junctions.