Surface engineering with Ar+/O2+ ion beam bombardment: Tuning the electronic and magnetic behavior of Ni80Fe20/La0.7Sr0.3MnO3/SrTiO3(001) junctions.

The magnetic and magnetotransport properties of Ni₈₀Fe₂₀/La_0.7Sr_0.3MnO₃ (NiFe/LSMO) bilayers were investigated after bombarding the LSMO surface with low-energy Ar⁺ or O₂⁺/Ar⁺ ion beams before the growth of the top NiFe layer. A variety of magnetic properties are revealed, including an asymmetric two-stepped hysteresis loop with an exchange bias loop shift, and alternatively, a symmetric two-stepped hysteresis loop with an enhanced coercivity. Polarized neutron reflectometry measurements provide details of the magnetic depth profile and interface layer magnetism at different temperatures. The LSMO surface modifications determine a complex magnetic and electric NiFe/LSMO interface having a strong effect on the magnetoresistance of the bilayer. Surface engineering based on ion beam bombardment is presented as a promising technique for optimizing the electronic and magnetic properties of NiFe/LSMO junctions for future device applications. [ABSTRACT FROM AUTHOR]