Synthetic Antiferromagnets with Steplike Hysteresis Loops and High- T_C Based on All-Perovskite La0.7Sr0.3Mn O3 Superlattices

Synthetic antiferromagnets with high Curie temperature (approximately 290 K) are realized among all-perovskite La0.7Sr0.3MnO3 (LSMO)/CaRu0.5Ti0.5O3 (CRTO) superlattices, which show antiferromagnetic (AF) interlayer exchange coupling (IEC) rather than traditional interfacial exchange coupling that is usually observed under the Curie temperature of the spacer. The system shows layer-resolved magnetic switching, resulting in sharp steplike hysteresis loops with magnetization plateaus depending on the repetition number of the stacking bilayers. This bilinear IEC can be easily changed to biquadratic IEC by change of orthorhombic NdGaO3(001) substrate to cubic (LaAlO3)0.3(SrAl0.5Ta0.5O3)0.7(001) substrate. The strength of AF IEC increases with decrease of temperature, and the modeling results suggest that both magnetic LSMO and the CRTO space layer play a role in this behavior. Remarkably, the LSMO/CRTO system shows controllability of AF-IEC behavior under a moderate magnetic field of hundreds of oersteds. These observations may have potential applications in future oxide spintronic devices.