Berlin 2005 – wissenschaftliches Programm
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MA: Magnetismus
MA 29: Magnetische Materialien
MA 29.3: Vortrag
Dienstag, 8. März 2005, 15:45–16:00, TU A060
Magnetic and structural characteristics of epitaxial Ge(Mn,Fe) diluted films — •Heiko Braak, R.R. Gareev, D. Rata, D.E. Bürgler, P.A. Grünberg, and C.M. Schneider — Institut für Festkörperforschung, Forschungszentrum Jülich GmbH, D-52425 Jülich, Germany
Novel Germanium-based Ge(Co,Mn) diluted magnetic semiconductor recently attracted attention due to their high Curie temperature (TC≈ 270K) and the possibility of straightforward integration into Si- and Ge-based technologies [1]. We prepare 100 nm-thick, epitaxial Ge100−(x+y)(Mnx,Fey) films with Mn and Fe concentrations of several at. % by growing Ge, Fe, and Mn seperately layer-wise at elevated temperature. From depth profiling with secondary ion mass spectrometry (SIMS) after annealing we find a homogenous distribution of Fe and Mn across the sample. The layered structure is gone.
We measure saturation magnetization mS versus temperature curves for a variety of (x,y) combinations with a SQUID magnetometer and find for fixed temperatures a non-trivial dependence of mS on x and y. Within a certain window in the (x,y) parameter space Ge100−(x+y)(Mnx,Fey) exhibits a TC of 350K and mS≈ 10 emu/cm2 at room temperature.
The temperature dependence of the remanent magnetization shows a curve composed of magnetic contributions with different phase-transition temperatures. The XRD-data gives evidence that our samples contains different clusters.
[1] F. Tsui, L. He, L. Ma, A. Tkachuk, Y. S Chu, K. Nakajima, and T. Chikyow, Phys. Rev. Lett. 91, 177203 (2003).