The Anisotropic Magnetocaloric Effect and Size-Dependent Magnetic Properties of Iron Particles

Abstract

We present a theoretical study on the anisotropic magnetocaloric effect and the size-dependent magnetic properties of Fe particles of radii in the range 25–150 Å. An observable increase has been found in the magnetization, of the low radii (25–75 Å) particles, by reducing the temperature to 4 K. The anisotropic isothermal change in entropy ΔSm has been calculated by taking the difference between maximum ΔSm along the easy [100] and hard [111] directions. The maximum anisotropic ΔSm is 0.015 J/kg K for a field change of 500 Oe along the [100] direction. The ΔSm temperature dependence exhibits a table-like plateau for small radii (25–75 Å) and in low fields below 300Oe. This enhances the relative cooling power (RCP) of the Fe element to be 8.11 J/kg for particles of 25 Å radius. Also, the calculation of anisotropic ΔTad was performed along the easy axis and showed an increase in the maximum value around 37% relative to the experimental conventional value.