  The magnetocaloric effect in exchange-coupled synthetic-antiferromagnet
multilayers is investigated experimentally and theoretically. We observe a
temperature-controlled inversion of the effect, where the entropy increases on
switching the individual ferromagnetic layers from anti-parallel to parallel
alignment near their Curie point. Using a microscopic analytical model as well
as numerical atomistic-spin simulations of the system, we explain the observed
effect as due to the interplay between the intra- and inter-layer exchange
interactions, which either add up or counteract to effectively modulate the
Curie temperature of the dilute ferromagnetic layers. The proposed method of
designing tunable, strongly magneto-caloric materials should be of interest for
such applications as heat-assisted spintronics and magnetic refrigeration.
