Regensburg 2016 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 41: Magnetic Coupling Phenomena

MA 41.1: Vortrag

Donnerstag, 10. März 2016, 09:30–09:45, H33

X-ray absorption studies of FeMn/Co exchange-bias systems — •Mathias Schmidt, Patrick Audehm, Gisela Schütz, and Eberhard Goering — Max-Planck-Institut für Intelligente Systeme

Exchange-bias (EB) systems play an important role for several applications in magnetic storage techniques and spintronics. Among those materials, FeMn/Co thin films are one of the most prominent examples due to their high coupling strength at the interface leading to a distinct unidirectional asymmetry of the hysteresis loop after field cooling. We used molecular beam epitaxy (MBE) to produce FeMn/Co systems on (100) oriented MgO substrates.

On these samples, we performed X-ray absorption (XAS) measurements making use of the X-ray circular magnetic dichroism (XMCD) to analyze the element-specific contributions to the uncompensated rotatable part of the magnetic moments close to the antiferromagnetic/ferromagnetic interface. Besides the well-known contribution of the Fe atoms to the uncompensated rotatable part we also found a notable amount of rotatable Mn moments. Additionally, we performed a quantification of the contributions of orbital and spin magnetic moments using the well-known sum rules. Finally, we were able to estimate the effective thickness of the uncompensated rotatable part of the AF layer proving that in deed a considerable part of the AF layer (up to 20% of the total thickness) is coupled to the Co layer on top in a ferromagnetic way. This experimental result is in contradiction to several theoretical models used for describing the EB, where the AF layer is mostly considered to be magnetically rigid.