Structure and magnetic properties of Fe/EuO granular films

AbtractWe produced Fe/EuO granular films by reactive co-evaporation, and measured their structural and magnetic properties using X-ray diffraction (XRD), transmission electron microscopy, and a superconducting quantum interference device magnetometer. The XRD patterns of Fe/EuO films deposited at substrate temperatures up to 200 °C show only weak peaks due to Fe, while films deposited at 400 °C show diffraction peaks due to Fe and EuO, indicating that an Fe/EuO granular film was formed. Magnetic measurements of the Fe/EuO granular films revealed the following: (i) the magnetization at 300 K shows typical ferromagnetic behavior, while that measured at 5 K shows non-saturating behavior with the magnetization above 15 kOe exceeding the saturation value at 300 K; (ii) the magnetization at a magnetic field of 10 kOe increases gradually with increasing temperature up to about 200 K, followed by a constant value, while that at 50 kOe shows an initial large value, which decreases to the constant value at around 200 K. These results indicate that the coupling between the magnetic moments of Fe and those of EuO is non-collinear, and that the moments gradually align themselves with an externally applied magnetic field.