Temperature-Dependent Mechanism of Magnetization Reversal in the Spintronic Electrode Material La0.67Sr0.33MnO3

We investigate magnetization-reversal processes in half-metallic epitaxial films of ${\mathrm{La}}_{0.67}{\mathrm{Sr}}_{0.33}{\mathrm{Mn}\mathrm{O}}_{3}$ on ${\mathrm{Sr}\mathrm{Ti}\mathrm{O}}_{3}$ (110) substrates. At 150 K, major-loop magnetization reversal (MLMR) occurs beyond minor-loop switching fields, implying that MLMR is limited by domain nucleation. At 280 K, MLMR overlaps with minor-loop switching fields if there are deliberately introduced precipitates, implying that the precipitates limit MLMR by pinning domain walls. To confirm that the precipitates pin domain walls at 280 K, we use a two-dimensional analogue of the Gaunt pinning model to show that pinning-limited switching occurs at fields consistent with the observed precipitate density of 0.3--2.0 \ensuremath{\mu}m${}^{\ensuremath{-}2}$. Our work demonstrates that comparing major and minor loops at any temperature of interest represents a simple way to check whether spintronic electrode materials show nucleation-limited MLMR, as circumstantially required for single-domain switching in micron-scale elements of ${\mathrm{La}}_{0.67}{\mathrm{Sr}}_{0.33}{\mathrm{Mn}\mathrm{O}}_{3}$ that represent spintronic electrodes [L. C. Phillips et al., Phys. Rev. Appl. 4, 064004 (2015)].