Field-free magnetization switching of synthetic antiferromagnets magnetic tunnel junction induced by spatially gradient spin texture

Synthetic antiferromagnets (SAFs) offer a promising pathway for the scaling of magnetic random access memory (MRAM) by eliminating stray fields; however, their practical potential is limited by the requirement of an external magnetic field for spin–orbit torque (SOT) switching. Notably, existing field-free magnetization switching approaches are limited to SAFs with weak interlayer exchange coupling (IEC), thereby compromising thermal stability and anti-interference capability. Here, we propose a spatial gradient spin texture (SGST) mechanism that achieves deterministic field-free magnetization switching in strong-IEC SAF systems. The SGST mechanism can generate an out-of-plane SOT torque that enables field-free magnetization switching without overcoming IEC potential barriers, as the antiferromagnetic order is preserved throughout the switching process. Based on this mechanism, we demonstrate field-free magnetization switching in SAF-based magnetic tunnel junction. This work paves the way toward high-density, interference-robust MRAM by overcoming the long-standing challenge of efficient magnetization control in strongly coupled SAF architectures.