Strain engineering of magnetocaloric effect in W/Gd/W/MgO structures

Abstract

Strain controlled magnetocaloric effect (MCE) accompanying a transition between ferromagnetic and paramagnetic phases has been revealed in multilayered W/Gd/W/MgO structures at Tc = 293 K. Mechanical stresses at the Gd/W interface controlled by internal stresses at the MgO substrate and depending on its crystallographic orientation, strongly affect magnetic part of entropy ΔSM and relative cooling power (RCP). Increase in thickness of Gd films from 100 nm up to 300 nm approaches the ΔSM and RCP values to those known for the bulk Gd samples. We found that higher internal stresses widen the temperature range in which a ferromagnet-paramagnet transition occurs. Since Gd based alloys are very perspective for magnetic refrigeration, obtained data can be used to predict how local internal stresses in the vicinity of structural defects (dislocations, twins etc) can affect MCE even in bulk Gd samples.