Reconfigurable Exchange Bias Enabled by Photoresponsive Liquid Crystal Networks in FeGa/IrMn Magnetic Heterostructures

Post-fabrication tunability of magnetic properties remains a key challenge for next-generation spintronic and adaptive magneto-electronic devices. Here, we report on a fully electrically contactless strategy to reversibly manipulate the magnetic response of an exchange-biased Ta/Fe80Ga20/Ir20Mn80/Ta multilayer stack through external light stimuli. A photoresponsive azobenzene-doped liquid crystal network (LCN) substrate is employed as an active support for the heterostructure capable of transferring controllable stress to the magnetostrictive FeGa layer under ultraviolet irradiation. This strain-mediated coupling induces a tunable uniaxial magnetic anisotropy in the device, enabling continuous, angular-dependent modulation of key magnetic parameters, including exchange bias and coercivity. Their variation reaches about 11% with respect to the unstressed state. Owing to the slow thermal relaxation kinetics of the LCN, the UV-induced magnetic state is retained after the illumination is switched off over timescales relevant for device operation and can be fully erased by subsequent green-light irradiation. Notably, both the magnitude and sign of the modulation are strongly angle-dependent, reflecting the interplay among stress-induced, magnetocrystalline, and interfacial (i.e., exchange coupling) anisotropies. This approach demonstrates a pathway toward reconfigurable, energy-efficient magnetic systems with remotely tunable functionality, offering significant advantages for miniaturized devices adaptable to dynamic, multi-stimuli environments.