Anti-irradiation reinforcement in NiFe/oxide composite structure by electronic reconstruction and structural stabilization for efficient magnetoresistive sensor in aerospace/radiotherapy applications

The construction of irradiation-tolerant anisotropic magnetoresistance (AMR) sensors is crucial for weak-field detection in scenarios of aerospace and radiotherapy. Presently, the utilization of the NiFe/oxide composite structure was considered to be an effective scheme to optimize the spin-dependent transport property; however, it exhibited poor anti-irradiation ability due to the crystal instability of oxide. Here, a strategy was proposed to break through the limitation based on the electronic reconstruction and structural stabilization. By introducing an oxygen-affinitive Hf intercalation into the Ta/MgO/NiFe/MgO/Ta multilayer, the electron coordination was modified to tune the 3d orbital occupancy of Fe, apparently boosting the s-d electron scattering and spin-related transport property. Meanwhile, the irradiation stability of electronic and crystal structures was effectively improved due to the emergence of the Hf–O–Mg bond with high dissociation energy. Therefore, we constructed a highly reliable AMR sensor with both the ultrahigh sensitivity of 3.1 mV/V/Oe and excellent irradiation-tolerant ability capable of resisting the γ-ray irradiation of 1000 Gy. These results not only build an important basis for the sensor application in the irradiation environment but also provide a possible idea for the anti-irradiation design in spintronic devices.