Modification of the Electrical Properties of a Bi_0.8Ca_0.2FeO₃/LaNiO₃/LaAlO₃ Heterostructure: Effect of 80 MeV O⁺⁷ Ion Irradiation

Ca-doped BiFeO₃/LaNiO₃/LaAlO₃ (BCFO/LNO/LAO) heterostructures have garnered significant interest due to their unique combination of ferroelectric, magnetic, and resistive switching properties due to interfaces and lattice mismatch/strain, leading to unique electronic properties. The roles of structural defects and oxygen vacancies are important in achieving the magnetic and electrical properties of BiFeO₃-based heterostructures. By generating defects, swift heavy ion irradiation can lead to changes in the structural, optical, electrical, and magnetic properties of the materials. The Ca-doped BiFeO₃ and LaNiO₃ heterostructure was grown upon LAO substrates using the pulsed laser deposition technique, ensuring high-quality interfaces and controlled thicknesses. The heterostructures were irradiated with 80 MeV O⁺⁷ ions at various ion fluence levels (5 × 10¹⁰ ions/cm² to 5 × 10¹² ions/cm²). The structure and crystalline orientation of the thin films were confirmed through x-ray diffraction, while the surface morphology was measured using atomic force microscopy. Irradiation-induced modifications of the structural strain and surface morphology were investigated in the context of internal annealing effect and defect formation. The resistive switching (RS) properties of the proposed devices were assessed by I–V measurement with sweeping 0 → 5 V → 0 →  − 5 V → 0, which shows that irradiation-induced defects play an important role in the electrical properties of the proposed heterostructure. Bipolar RS behavior was also verified with the conduction mechanism, indicating that the ohmic and space-charge-limited conduction mechanism plays an important role in irradiated BCFO/LNO/LAO heterostructures.

Graphical representation of the defect formation and RS behavior due to varying ion fluence as a function of RMS roughness and strain.