FeCo nanowires with enhanced heating powers and controllable dimensions for magnetic hyperthermia

A detailed study of the magnetic properties and heating capacities of electrodeposited FeCo nanowires with varying lengths (2-40 μm) and diameters (100 and 300 nm) is reported. We find that specific absorption rate (SAR) increases rapidly with increasing wire length up to 10 μm, followed by a gradual increase for larger lengths. Magnetic and hyperthermia measurements have revealed the important effect of dipolar interactions between the nanowires on their magnetic and inductive heating responses. Both calorimetric and AC magnetometry methods consistently show that the physical movement contribution of the nanowires to the SAR is small, and that for applied fields exceeding the coercive field, the nanowires tend to align parallel to the field, thus enhancing the SAR. Maximum SAR values of ∼1500 W/g have been achieved for the largest wires at H = 300 Oe and f = 310 kHz.