Berlin 2008 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 26: III-V semiconductors I

HL 26.2: Vortrag

Dienstag, 26. Februar 2008, 16:00–16:15, EW 202

Magnetic properties of GaMnN/AlGaN Heterostructures — •D. Mai, A. Bedoya Pinto, D. Ruttke, J. Malindretos, A. Rizzi, H. Schuhmann, and M. Seibt — IV. Physikalisches Institut and Virtual Institute of Spin Electronics (VISel), Georg-August-Universität Göttingen, D-37077 Göttingen, Germany

GaMnN is a prototype GaN-based dilute magnetic semiconductor. In the past we have carefully studied the growth process and epitaxial GaMnN layers with diluted concentration of Mn up to some percent have been grown. They reproducibly show a room temperature magnetization, however with a weak saturation M_S = 0.03 emu cm⁻³ and a small coercive field of 250 Oe. With the aim of investigating the effect of the Fermi level position relative to the Mn induced impurity band deep in the energy gap, AlGaN/GaMnN/AlGaN heterostructures have been grown. In fact due to the polarization charges at the interfaces a strong band bending is expected in the structure, which might change the Mn charge state in certain regions of the GaMnN layer. Magnetization measurements by SQUID show ferromagnetic behaviour at room temperature with saturation magnetization by a factor 40 higher than in the samples described above. Diverse heterostructure configurations have been characterized concerning the magnetic and electric properties and the results are discussed with reference to the assumed double-exchange mechanism for the magnetic coupling.