Dresden 2009 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 9: Poster 1
HL 9.50: Poster
Montag, 23. März 2009, 14:30–17:00, P2
Optical and magnetic properties of MnS in low dimensions — •Manuel Demper1, Limei Chen1, Christine Bradford2, Hans-Albrecht Krug von Nidda3, Kevin A. Prior2, Alois Loidl3, and Wolfram Heimbrodt1 — 1Departement of Physics and Material Science Center, Philipps University, Marburg — 2School of Engineering and Physical Sciences, Heriot-Watt University, Edinburgh — 3Center for Electronic Correlation and Magnetism, University Augsburg
The continuously decrease of magnetic structures sooner or later reaches fundamental boundaries. Hence, it is essential to understand the magnetic interactions in low dimensions. Therefore we investigated the transition from 3D-2D on a series of MBE grown zinc blende MnS-layers with various thicknesses between 1ML and 8.6nm by using photoluminescence and SQUID techniques. The PL spectra of these antiferromagnetic MBE-layers exhibit a strong yellow emission band, which belongs to the internal d-d transition of the manganese ions. This 4T1→6A1 transition offers an optical access to the magnetic properties of MnS. Thus, the temperature dependence of the yellow emission bands shows a significant red-shift at low temperatures caused by the energy relaxation of the Mn d-states at the para- to antiferromagnetic phase transition. Surprisingly, there is no clear indication for a reduced Néel-temperature down to one monolayer. These optical results are confirmed by SQUID measurements. Besides the antiferromagnetic phase transition, the thinnest MnS films additionally exhibit a clear ferromagnetic phase below 150K. The unique behaviour will discussed in detail.