Regensburg 2007 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 15: Poster:ThinFilms(1-33),Transp.(34-49),ExchBias(50-56),
Spindynamics(57-70),Micro-nanostr.Mat.(71-82),
Particles/Clust.(83-88), Mag.Imag./Surface(89-96),
Spinelectronics(97-109), Theory/Micromag.(110-116),
Spinstruct/Phasetr.(117-128),Magn.Mat.(129-139),
Aniso.+Measuring(140-145), MolMag.(146-152),
MSMA(153-156)

MA 15.18: Poster

Dienstag, 27. März 2007, 15:00–19:00, Poster A

Imaging magnetic structures in Ga_1−xMn_xAs films by low temperature laser scanning microscopy — •Stefan Guenon¹, Michael Wagenknecht¹, Sebastian Goennenwein², Rudolf Gross², Dieter Koelle¹, and Reinhold Kleiner¹ — ¹Physikalisches Institut-Experimentalphysik II, Universität Tübingen, Auf der Morgenstelle 14, D-72076 Tübingen, Germany — ²Walther-Meißner-Institut, Bayerische Akademie der Wissenschaften, Walther-Meißner Straße 8, D-85748 Garching, Germany

Diluted magnetic semiconductor alloys, such as epitaxial Ga_1−xMn_xAs films, have attracted considerable interest. They are potentially useful for spintronics applications in which information processing and storage is achieved by utilizing the electron spin. We used low temperature laser scanning microscopy on a hall bar like structure made of a 20 nm thick Ga_0.96Mn_0.04As film grown on a (100)-oriented GaAs substrate by low-temperature molecular beam epitaxy. An unusual strong thermoelectric signal was observed as a response to the pulsed laser beam on the structure. The signal can be modeled by an electrical dipole induced in the area of the laser spot. In a temperature range well below the Curie temperature T_C ≈ 70 K where the in-plane magnetic anisotropy of the ferromagnetic film is biaxial we were able to image structures that are similar to already observed ferromagnetic domains in Ga_1−xMn_xAs films by Kerr microscopy.