Influence of interface coupling on spin-flop critical fields in ferromagnet-antiferromagnet coupled systems

A fundamental parameter for coupled ferromagnet/antiferromagnet systems is the effective exchange coupling at the interface between the two materials. This parameter, however, remains difficult to measure because the exchange-bias also depends on the interface roughness and the degree of noncompensation in the antiferromagnet top layer. We investigate, theoretically, a different quantity, the spin-flop transition in the antiferromagnet. We find that the shift in the spin-flop field, H-sf, depends critically on the exchange coupling at the interface and is only weakly dependent on the noncompensation. Thus we suggest a method for determining the magnitude and sign of the interface coupling from magnetization measurements. We also discuss how the spin-flop field depends on the thickness of the antiferromagnet.