Magnetoresistance and second harmonic Hall measurement of Pt/CoFe₂O₄ bilayers

CoFe₂O₄ (CFO), a room temperature ferrimagnetic insulating spinel ferrite, is a promising candidate for energy efficient spintronics. Magnetic proximity effect was believed to be absent in Pt/CFO bilayers grown by sputtering or pulsed laser deposition (PLD), but was recently observed in Pt/CFO (001) bilayers grown entirely by molecular beam epitaxy (MBE) [Amamou, Walid et al. Physical Review Materials 2, 011401 (2018)]. Here, we report the observation of magnetic proximity effect in ex situ sputtered Pt on MBE grown CFO (001) at room temperature. Angle dependent magnetoresistance measurements in the direction insensitive to spin Hall magnetoresistance (SMR) indicates that magnetic proximity effect is a relatively robust phenomenon. We also studied high quality CFO (111) on multiferroic LuFeO₃ (111) using MBE, since the impact of crystal orientation of CFO on magnetic interaction has been reported to be significant between Pt and CFO. In the same Pt/CFO (001) and Pt/CFO (001) stacks we also carried out the second harmonic Hall measurement and found Nernst effect dominating the signal.