Magnetocaloric effect in the Fe/FeAl/Fe structure

The magnetocaloric properties of a thin FeAl(5) layer between strong Fe ferromagnets in the layered system Cr(50)/CoSm(30)/Fe(1)/Fe$_x$Al$_{1-x}$(5)/Fe(5)/Ta(5) ($x$ = 0.55) have been studied experimentally. An increase in the magnetcaloric efficiency $\Delta S/\Delta H$ is expected in such structures ($\Delta S$ is the change in magnetic entropy, ($\Delta H$ is the magnitude of the applied magnetic field), due to the exchange coupling at the interfaces between the interlayer and the surroundings. $\Delta S/\Delta H$ values have been determined from measurements of magneto-optical rotation curves using Maxwell's relation. A sharp increase in this parameter is discovered when the measurement temperature is increased to $T^*$ = 400 K. A further increase in temperature above $T^*$ led to destruction of the structure due to mixing of the layers. As the Fe concentration in the interlayer decreased below the value $x$ = 0.55, the magnetization of the interlayer and the $T_C$ value in it strongly decreased.