Magnetic control of the zero-magnetization ferromagnet Sm1-xGdxAl2
Résumé
X-ray magnetic circular dichroism experiments have been performed up to +/- 17 T to investigate the magnetic configuration and magnetization reversal of an original zero-magnetization ferromagnet Sm1-xGdxAl2 (x = 0.028), both as a single epitaxial layer and as a pinning layer in an exchange-coupled system. The Sm0.972Gd0.028Al2 single layer appears to exhibit an extraordinary large coercivity that exceeds 20 T below its magnetic compensation (T-comp). Despite such huge magnetic stability in the single layer, interface exchange coupling in the bilayer drives the formation of domains in Sm0.972Gd0.028Al2 and their reversal upon field, both below and at magnetic compensation. Increasing the cooling field yields the increase in exchange-favored domains in Sm0.972Gd0.028Al2, surprisingly also at T-comp, whereas, Zeeman energy does not favor this specific orientation neither at compensation nor during the cooling process. We propose a possible scenario for those domains' formation and highlight the way the external magnetic field may tune the magnetic configuration in such a zero-magnetization ferromagnet. The cooling field also consequently influences the SmAl2 magnetization reversal which is biased by pinned magnetic components in Sm0.972Gd0.028Al2; the bias field is satisfactorily explained in considering different pinned contributions with opposite magnetic orientations.