distribution and thermal conductivities of the Fe
film. (a) Linear regions of the third-harmonic voltage versus the applied frequency at various applied alternating currents (AC) ranging from 5 to 10 μA. (b) Thermal conductivities of Fe3O4 film with different film thicknesses (100, 300, and 400 nm) with respect to the applied AC (5 to 10 μA). Variation in the thermal conductivity with modulation of the input AC current could be assumed as measurement errors in thermal conductivity.