Devices are described that include a multi-layered structure that is non-magnetic at room temperature, and which comprises alternating layers of Co and at least one other element E (such as Ga, Ge, and Sn). The composition of this structure is represented by Co1-xEx, with x being in the range from 0.45 to 0.55. The structure is in contact with a first magnetic layer that includes a Heusler compound. An MRAM element may be formed by overlying, in turn, the first magnetic layer with a tunnel barrier, and the tunnel barrier with a second magnetic layer (whose magnetic moment is switchable). Improved performance of the MRAM element may be obtained by placing a pinning layer between the first magnetic layer and the tunnel barrier.