Soft x-ray magnetic circular dichroism study of Mn-Ir/Co-Fe bilayers with giant exchange anisotropy

摘要

Soft x-ray magnetic circular dichroism (XMCD) and element-specific magnetic hysteresis (ESMH) measurements were performed in transmission mode on Mn_(73)Ir_(27) 10 nm/Co_(70)Fe_(30) 2 nm bilayers with different chemical orderings of the Mn-Ir layer. The unidirectional anisotropy constant was 0.55 erg/cm~2 for the disordered Mn-Ir layer and 1.18 erg/cm~2 for the ordered Mn-Ir layer. The XMCD signal of Mn was observed, which means the induced ferromagnetic component of Mn spins through the exchange coupling at the interface. No vertical offset of the Mn ESMH loops was observed for either the disordered or the ordered bilayers, which means that insignificant uncompensated Mn spin was pinned at the interface to induce exchange bias on the Co-Fe layer.