Carrier injection properties in spin–orbit coupling structure based on a correlated electronic ferromagnetic system

Abstract

Carrier injection effects on phase-field domain structures are displayed between BiFeO3 and La0.4Gd0.1Sr0.5CoO3 thin films prepared by pulsed laser deposition, epitaxially grown on LaAlO3 (100) substrates. The leakage current and magnetoresistance (MR) in the fabricated BiFeO3/La0.4Gd0.1Sr0.5CoO3/LaAlO3 heterostructure were measured under 0.2, 0.4 and 0.6 T at 80–300 K. The BiFeO3/LGSCO heterojunction exhibits the carrier transfer of the metal–insulator transition and a positive MR effect at 219–250 K. The electric-conductivity mechanism below the Curie temperature, TC, is dominated by Poole–Frenkel emission. The BiFeO3/LGSCO pn junction shows rectifying behavior between 80–300 K. The energy bands of the heterojunction were modified by the morphology of the interface, the magnetic domain, spin polarization and interface tensile strain due to external magnetic perturbations. The strain and magnetic field-modified domain wall and the carrier density at the BiFeO3/LGCO interface were characterized by atomic force microscopy. The domain and phase separation of LGSCO/BiFeO3 changed with strain, structural defects, grain size and boundary and the modified concentration of carriers. Additionally, the BiFeO3/La1−xGdxSrCoO3 heterostructure shows a positive colossal MR effect at 80–300 K and an metal–insulator phase transition was observed around TC 219.5 K for 0.6 T, 220 K for 0.4 T and 249.7 K for 0.2 T.