G.  Gubbiotti, Malago, P., Fin, S., Tacchi, S., Giovannini, L., Bisero, D., Madami, M., Carlotti, G., Ding, J., Adeyeye, A. O., and Zivieri, R., ?Magnetic normal modes of bicomponent permalloy/cobalt structures in the parallel and antiparallel ground state?, Physical Review B, vol. 90, pp. 4419?4419, 2014.