Ferroelectric and magnetic properties of multiferroic BiFeO₃-La_0.7Sr_0.3MnO₃ heterostructures integrated with Si (100)

We report on the electrical, ferroelectric, and magnetic properties of BiFeO₃ (BFO)-La_0.7Sr_0.3MnO₃ heterostructures deposited epitaxially onto Si(100) substrates. Temperature dependent (200-350 K) current-voltage (I-V), switching spectroscopy piezo-response force microscopy (SSPFM), and temperature dependent (5-300 K) anisotropic magnetization measurements have been performed. The BFO (100-nm thick)-based device structures were fabricated with a 250 nm thick La_0.7Sr_0.3MnO₃ bottom electrode and 200 μm circular top Pt electrodes. I-V measurements performed at various temperatures indicated that the devices retained their as-deposited characteristics and exhibited non-leaky behavior up to at least 50 cycles. The temperature-dependent measurements showed clear diode-like behavior and resistive (hysteretic) switching behaviour. Characteristic butterfly loops (of several cycles) were observed in the PFM amplitude signals of the BFO film. In addition, the phase signal indicated a clear (180°) switching behavior at the switching voltage of 4-5 V, providing unambiguous evidence for the occurrence of ferroelectricity in BFO films integrated on Si (100). The temperature- and angle-dependent zero field cooled isothermal (5 K) magnetization measurements were consistent with the presence of uniaxial magnetic anisotropy. This work makes an important step for the fabrication of CMOS-compatible BFO devices for memory applications.