Antiferromagnetic Mn on Fe(001) studied by spin-polarized scanning tunneling microscopy

In this paper, a detailed analysis of the spin polarization of the surface of thin antiferromagnetic Mn films on Fe(001) is presented. Spin-polarized scanning tunneling microscopy (STM) measurements allows the study of the spin dependent tunneling current through a well defined barrier, a vacuum gap, as a function of the bias voltage. This offers the possibility to study magneto-transport phenomena at antiferromagnetic films in direct contact to a ferromagnet. Bias-dependent measurements performed at the Mn films on Fe(001) show a rather complex behavior of the spin contrast as function of the bias voltage. These experimental observations can be explained with model calculations based on ab-initio band structures. Based on the calculations, the spin contrast at the Mn surfaces can solely be explained by bulk states and no surface states are necessary.