SKM 2021 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 23: Focus Session: Highlights of Materials Science and Applied Physics III (joint session DS/HL)

HL 23.3: Vortrag

Freitag, 1. Oktober 2021, 11:45–12:00, H1

Bulk and interfacial effects in the Co/Ni _x Mn _100−x exchange-bias system due to creation of defects by Ar ⁺ sputtering — •Tauqir Shinwari¹, Ismet Gelen¹, Yasser A. Shokr^1,2, Ivar Kumberg¹, Ikram Ullah³, Muhammad Sajjad³, M. Yaqoob Khan³, and Wolfgang Kuch¹ — ¹Freie Universität Berlin, Arnimallee 14, Berlin 14195, Germany — ²Faculty of Science, Department of Physics, Helwan University, 17119 Cairo, Egypt — ³Department of Physics, Kohat University of Science and Technology, Kohat, Khyber Pakhtunkhwa 26000, Pakistan

A series of experiments is carried out to identify the contribution of interface and bulk antiferromagnetic (AFM) spins to exchange bias (EB) in ultrathin epitaxial ferromagnetic (FM)/AFM bilayer samples. These are single-crystalline AFM Ni _x Mn _100−x and FM Co layers on Cu ₃ Au(001), in which structural or chemical defects are introduced by controlled Ar ⁺ sputtering at the surface of the AFM layer or at a certain depth inside the AFM layer. Comparison of the magnetic properties measured by magneto-optical Kerr effect for sputtered and non-sputtered parts of the same sample then allows a precise determination of the influence of sputtering on the AFM layer during the sample preparation. The results show that the creation of defects in the bulk of the AFM layer enhances the magnitude of EB and its blocking temperature, but not the ones at the interface. We also observed that the deeper the insertion of defects in the AFM layer, the higher the EB field and the larger the coercivity. These findings are discussed as the effect of additional pinning centers in the bulk of the AFM layer.