Tunable ferromagnetic and antiferromagnetic interfacial exchange coupling in perpendicularly magnetized L10-MnGa/Co2FeAl Heusler bilayers

In this work, we report a tailorable exchange coupling (J(ex)) at the Mn62Ga38/Co2FeAl interface, where Mn62Ga38 and Co2FeAl alloys are tetragonal Heusler alloy with high perpendicular magnetic anisotropy and typical cubic Heusler alloy with soft magnetism, respectively. As the post annealing temperature (T-a) is lower than 375 degrees C, the J(ex) is ferromagnetic with strength controllable from 7.5 to 0.5 erg/cm(2). Interestingly, as T-a increases higher than 400 degrees C, an antiferromagnetic J(ex) of -5.5 erg/cm(2) is observed. The ferromagnetic/antiferromagnetic transition is further evidenced by the spin dependent transport property of the magnetic tunnel junctions with Mn62Ga38/Co2FeAl as electrode. Based on structure characterization, the variation of J(ex) during annealing is discussed. (C) 2014 AIP Publishing LLC.