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MA: Fachverband Magnetismus
MA 33: Magnetic Coupling Phenomena/ Exchange Bias
MA 33.9: Talk
Wednesday, March 28, 2012, 17:30–17:45, EB 202
Probing antiferromagnetism in NiMn/Ni/(Co)Cu3Au(001) single-crystalline epitaxial thin films — •Muhammad Yaqoob Khan, Chii-Bin Wu, and Wolfgang Kuch — Institut für Experimentalphysik, Freie Universität Berlin, 14195 Berlin, Germany
Antiferromagnetism of equi-atomic single-crystalline NiMn thin film alloys grown on Ni/Cu3Au(001) is probed by means of magneto-optical Kerr effect (MOKE). Thickness-dependent coercivity (Hc) enhancement of NiMn/Ni/Cu3Au(001) showed that NiMn thicker than 7 atomic monolayers (ML) order antiferromagnetically at room temperature. It is found that NiMn can couple to out-of-plane (OoP) as well as in-plane (IP) magnetized Ni, the latter stabilized by Co under-layer deposition. The antiferromagnetic (AFM) ordering temperature (TAFM) of NiMn coupled to OoP Ni is found to be much higher (up to 110 K difference) than in the IP case, for otherwise identical interfacial conditions. This is attributed to the magnetic proximity effect in which the ferromagnetic (FM) layer substantially influences the TAFM of the adjacent AFM layer and can be explained by either (i) a higher interfacial coupling strength or/and (ii) a thermally more stable NiMn spin structure when coupled to Ni magnetized in OoP direction than in IP. An exchange-bias effect could only be observed for the thickest NiMn film studied (35.7 ML); the exchange-bias field (Heb) is higher in the OoP exchange-coupled system than in the IP one due to the same reason/s.