Berlin 2018 – wissenschaftliches Programm

Bereiche | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe

MA: Fachverband Magnetismus

MA 21: Poster I

MA 21.15: Poster

Dienstag, 13. März 2018, 09:30–13:00, Poster A

Influence of Bulk and Interface Defects in the Antiferromagnetic Layer for the Exchange- Bias Effect — •Tauqir Tauqir¹, M. Yaqoob Khan², Ikram Ullah², M. Sajjad², Izran Ullah², Yasser A. Shokr¹, and Wolfgang Kuch¹ — ¹Institut für Experimentalphysik, Freie Universität Berlin, Arnimallee 14, 14195 Berlin, Germany — ²Kohat University of Science and Technology, Kohat 26000, Khyber Pakhtunkhwa, Pakistan

A series of experiments is carried out to identify the fundamental mechanisms leading to the exchange bias effect in ultrathin epitaxial bilayer samples ferromagnetic/antiferromagnetic (FM/AFM) on a Cu₃Au(001) substrate. The studied samples are bilayers of single-crystalline antiferromagnetic Ni₂₅Mn₇₅ and ferromagnetic Co layers, deposited under UHV, in which structural or chemical defects are deliberately introduced by Ar⁺ ion bombardment for short times at the FM/AFM interface or at a certain depth of the AFM layer. The approach is to influence both the interface coupling as well as the pinning sites inside the AFM material by the controlled insertion of disorder. Comparison of the magnetic properties measured by magneto-optical Kerr effect then allows a precise determination of the influence of the Ar⁺ ion bombardment of the AFM layer. We find that the interfacial and sandwiched defects result in decrease and increase of the exchange bias field (H_eb), respectively. We interpret this as, within the AFM layer, sandwiched defects leading to the formation of domains, which in turn give rise to uncompensated pinned moments that are responsible for the increased H_eb as predicted in the domain-state model.