Toward Flexible Neuromorphic Spintronics: Field-Free Switching of Synthetic Antiferromagnets on Polyimide Substrates

Achieving fully electrically controlled magnetization switching of magnetically compensated synthetic antiferromagnets grown on flexible substrates would significantly advance high-density wearable memory and neuromorphic spintronic applications. Here, we illustrate the field-free spin-orbit-torque (SOT)-driven perpendicular magnetization switching in high-quality Pt/CoPt/Ru/CoTb synthetic antiferromagnets grown on polyimide substrates, which exhibit room-temperature compensated magnetization and enhanced anomalous Hall resistance at remanence. A 3% tensile strain induces a 390 Oe shift in the interlayer exchange coupling field and reduces the field-free SOT switching ratio to ∼28%. Crucially, the near-linear nonvolatile synaptic plasticity and neuronal nonlinearity of this field-free SOT switching are preserved under bending, stretching, and tensile fatigue. Leveraging these experimentally measured synaptic and neuronal characteristics, we computationally implemented a fully connected neural network, achieving simulated recognition accuracies exceeding 95.8% for handwritten digits and 86.2% for fashion products. These results offer an effective method for developing flexible spintronic devices.