Control of Magnetization-Reversal Mechanism via Uniaxial Anisotropy Strength in La0.67Sr0.33Mn O3 Electrodes for Spintronic Devices

Spintronic device performance depends critically on magnetization reversal mechanisms, but these are rarely imaged in order to verify correct operation. Here we use magnetometry and magnetic imaging to study thin films and patterned elements of highly spin-polarized La0.67Sr0.33MnO3 grown epitaxially on NdGaO3 substrates whose crystallographic orientation determines magnetic anisotropy strength. Small anisotropy yields gradual magnetization reversal via nucleation and propagation of small-needle domains, whereas large anisotropy yields a single nucleation event resulting in sharp and complete magnetization reversal. We explain these observed differences using micromagnetic simulations, and exploit them in order to quantify the effect of La0.67Sr0.33MnO3 electrode behavior on spin signals from hypothetical devices. Our work, therefore, highlights the dramatic discrepancies that can arise between the design and performance of spintronic devices.