Soliton-Mediated Magnetic Reversal in an All-Oxide-Based Synthetic Antiferromagnetic Superlattice

Abstract

All-oxide-based synthetic antiferromagnets (SAFs) are attracting intense research interest due to their superior tunability and great potentials for antiferromagnetic spintronic devices. In this work, using the La2/3Ca1/3MnO3/CaRu1/2Ti1/2O3 (LCMO/CRTO) superlattice as a model SAF, we investigated the layer-resolved magnetic reversal mechanism by polarized neutron reflectivity. We found that the reversal of LCMO layer moments is mediated by nucleation, expansion, and shrinkage of a magnetic soliton. This unique magnetic reversal process creates a reversed magnetic configuration of the SAF after a simple field cycling. Therefore, it can enable vertical data transfer from the bottom to the top of the superlattice. The physical origin of this intriguing magnetic reversal process could be attributed to the cooperation of the surface spin-flop effect and enhanced uniaxial magnetic anisotropy of the bottom LCMO layer. This work may pave a way to utilize all-oxide-based SAFs for three-dimensional spintronic devices with vertical data transfer and high-density data storage.

Measurement Geometry and Hydrostatic Pressure‐Dependent Magnetoresistance in All‐Oxide‐Based Synthetic Antiferromagnets

“…Note that the two LCMO layers have the same strain state, but the octahedral distortion/tilting imparted by the substrate will cause the bottommost LCMO layer to have a stronger uniaxial magnetic anisotropy and a larger coercive field, thereby the magnetization reversal of the upper and lower LCMO layers are no longer equivalent. [ 38 ] The specific magnetization configuration of these two LCMO layers for each plateau is illustrated by a corresponding set of solid black arrows in Figure 1d.…”

“…[34] These SAFMs exhibit remarkable characteristics, including the controllable IEC and a notable crossover from spin-polarized tunneling to Ruderman-Kittel-Kasuya-Yosida-type exchange interaction by varying the Ti doping level in the spacer layer. [35][36][37][38][39][40][41] For example, for the insulating CaRu 0.5 Ti 0.5 O 3 (CRTO) spacer layer, the spin-polarized electrons from a half-metallic La 0.67 Ca 0.33 MnO 3 (LCMO) layer can transfer through electron tunneling to adjacent LCMO layers. [34] To measure TMR, we need to fabricate high-quality magnetic tunnel junctions (MTJs) with a CaRuO 3 (CRO) bottom electrode and conduct the measurement in the CPP geometry.…”