Dresden 2011 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 63: [MA] Surface magnetism III

O 63.4: Vortrag

Donnerstag, 17. März 2011, 11:45–12:00, HSZ 103

NiO thickness and temperature dependent coercivity of Fe layers grown on NiO/Ag (100) — •Anita Dhaka, Dirk Sander, and Jürgen Kirschner — Max-Planck-Institut für Mikrostrukturphysik, Weinberg 2, 061120 Halle (Germany)

We have performed temperature dependent magneto-optical kerr effect (MOKE) measurements in the longitudinal geometry to investigate the coercivity of 6 monolayers (ML) Fe on NiO deposited on Ag (100). MOKE indicates that the coercivity of Fe on NiO strongly depends on the thickness of NiO, and this effect is temperature dependent. We find that the coercivity of 6 ML films deposited on 20 ML NiO of H_c=142 mT at 300 K,which increases to 172 mT at 150 K. For 40 ML NiO, the coercivity is 148 mT at 300 K, and 284 mT at 150 K. 6 ML Fe on Ag (100) show a constant H_c of 9±3 mT from 150 K to 470 K. The change of coercivity with temperature is reversible up to T=470 K. At higher temperature intermixing is found by Auger elctron dpectroscopy, and the magnetic behavior is no longer reversible upon cooling. No increase of coercivity is observed for Fe films on 20 ML and 40 ML NiO at 470 K. Temperature dependence of the coercivity is ascribed to presence of antiferromagnetic NiO, and our data indicate a Neel temperature of 20 ML NiO of approximately 470 K [1]. Financial support by SFB 762 is gratefully acknowledged. [1] D. Alders, L. H. Tjeng, F. C. Voogt, T. Hibma, G. A. Sawatzky, C. T. Chen, J. Vogel, M. Sacchi, S. Iacobucci, Phys. Rev. B 57, 11623, (1998).