Hysteresis measurement of individual multilayered Fe-Ga/Cu nanowires using magnetic force microscopy

We have investigated nano-scale magnetic structures to learn how magnetic behaviors differ from what is observed in bulk materials. In this study, we have measured the magnetic hysteresis of individual multilayered nanowire using a magnetic force microscopy (MFM). The nanowires were composed of low-aspect ratio segments of iron-gallium (Galfenol, Fe80Ga20) and copper layers. Individual wires were released from nano-porous anodized aluminum oxide (AAO) templates and separated from other nanowires to avoid significant interactions between nearby nanowires. In this experiment, structures with aspects ratios c/a of similar to 3 were studied. Different MFM phase magnitudes in response to the interaction of magnetic film coated MFM tips and Fe-Ga/Cu nanowire were observed as a function of applied external magnetic field (-850 Oe < H < 850 Oe). Amplitude differences between bright and dark responses in MFM images were used to demonstrate hysteresis. Coercivity measured was about 125 Oe, which is almost same as the coercivity value (similar to 150 Oe) of a nanowire array measured with a vibrating sample magnetometer (VSM). When fields are applied perpendicular to the nanowires, the hysteresis loops sheared, indicating that the easy axis is along the nanowire axis. Remanence magnetizations of an individual nanowire and a nanowire array were compared to demonstrate inter-wire magnetostatic dipolar interaction. (C) 2013 American Institute of Physics.