Berlin 2008 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 18: Poster I : Bio Magn. (1-2); Mag.Imgaging (3-9); Magn. Semiconductors (10-16); Half Metals & Oxides (17-20); Coupl.Phenomena (21-27); Magn. Mat. (28-41); Micro & Nanostr. Magn. Materials (42-61); Micro Magn. (62-64); Surface Magnetism (65-70); Transport Phenomena (71-85)

MA 18.15: Poster

Dienstag, 26. Februar 2008, 15:15–18:30, Poster E

Magnetic properties of patterned (Ga,Mn)As films — •Matthias Sperl, Frank Hoffmann, Daniel Neumaier, Ursula Wurstbauer, Florian Götz, Christian H. Back, and Günther Bayreuther — Institut für Experimentelle Physik, Univ. Regensburg, D-93040 Regensburg

To study transport properties of the ferromagnetic semiconductors (Ga,Mn)As structures of sub-micron dimensions are frequently used. The question whether magnetic properties in laterally confined (Ga,Mn)As structures are different from extended films has been investigated in the present work.

(Ga,Mn)As films were epitaxially grown on GaAs (001) by means of molecular beam epitaxy. The films are patterned by electron beam lithography and ion etching into large area arrays of uniform circular dots with diameters between 500 nm and 10 micron. The magnetic properties of the dot arrays are measured with magnetooptical Kerr effect and superconducting quantum interference device (SQUID) magnetometry. Additionally, the magnetic anisotropy of single dots is studied with spatially resolved FMR. We find a large increase of the coercive field in patterned films. Furthermore, the influence of the dot size on the Curie temperature and on the magnetic anisotropy is discussed.