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 15.17: Poster
Dienstag, 27. März 2007, 15:00–19:00, Poster A
Magnetotransport and magnetic anisotropy in (Ga,Mn)As thin films — •Matthias Althammer, Andreas Brandlmaier, Sebastian W. Schink, Matthias Opel, Rudolf Gross, and Sebastian T. B. Goennenwein — Walther-Meissner-Institut, Bayerische Akademie der Wissenschaften, 85748 Garching, Germany
Magnetic anisotropy governs the magnetization orientation in ferromagnetic thin films, and therefore is relevant both for basic research as well as for applications. Using magnetotransport measurements, we investigate the magnetic anisotropy of the prototype ferromagnetic semiconductor (Ga,Mn)As. We patterned a 20 nm thick, (001)-oriented Ga0.96Mn0.04As film into Hall-bar mesa structures with optical lithography and etching. The anisotropic magnetoresistance (AMR) is then measured with the external magnetic field applied in the film plane. We observe clear steps at magnetic fields |H1| and |H2| in both the longitudinal (sheet) and the transverse (planar Hall) magnetoresistance. This shows that the AMR is determined by one single, macroscopic magnetic domain, which abruptly switches from one easy axis to another. The fields H1 and H2 characteristically depend on the orientation of the externally applied magnetic field with respect to the current direction. We show that this dependence allows to quantitatively determine the orientation of the easy in-plane magnetic axes as well as the ratio of the magnetic anisotropy contributions. We furthermore discuss the influence of temperature, crystalline strain and specimen shape on the in-plane magnetic anisotropy.