Heterojunction*

EuO_1-x combines several interesting properties: large magneto-optical effects, colossal magneto-resistance, and enhanced Curie temperature due to bound magnetic polarons. EuO_1-x is also one of a very few ferromagnetic insulators and, as an ultra thin film, very sensitive to interface effects. Investigation into the affect of ferroelectric substrates on the ferromagnetic properties of EuO_1-x can provide deep insights into how one can manipulate magnetism by changing interface charge populations. Utilizing pulsed laser deposition, a thin film (20nm) of ferroelectric BaTiO₃ was grown on top of a thin film (15nm) of ferromagnetic EuO_1-x. X-ray diffraction indicates the presence of high quality crystalline thin films of EuO_1-x and BaTiO_3. Magneto optical Kerr effect (MOKE) spectroscopy and magneto-resistance measurements indicate a temperature dependent signature of anti-ferromagnetic magnetoelectric coupling of the ferroelectric/ferromagnetic heterostructure. This study sheds new light on the modulation of magnetoelectric coupling at a device interface.