Regensburg 2007 – wissenschaftliches Programm

Bereiche | Tage | Auswahl | Suche | Downloads | Hilfe

HL: Fachverband Halbleiterphysik

HL 19: Spin controlled transport I

HL 19.5: Vortrag

Dienstag, 27. März 2007, 11:45–12:00, H14

Lithographic engineering of anisotropies in (Ga,Mn)As — •K. Pappert¹, S. Hümpfner¹, M. Sawicki², J. Wenisch¹, K. Brunner¹, C. Gould¹, G. Schmidt¹, T. Dietl², and Laurens W. Molenkamp¹ — ¹Physikalisches Institut (EP3), Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany — ²Institute of Physics, Polish Academy of Sciences, al. Lotnikow 32/46, PL-02668 Warszawa, Poland

The focus of ferromagnetic semiconductor research is shifting from material issues towards device functionalities. So far demonstrated device concepts are mainly based on the strong magnetic anisotropy present in materials like (Ga,Mn)As. However, until now all regions of a device always inherited the magnetic anisotropy properties of the (Ga,Mn)As layer. Here we present a method to locally engineer the magnetic anisotropy by lithographic patterning and the associated strain relaxation. SQUID magnetometry studies on arrays of structures and transport studies on individually contacted nanobars will be shown, evidencing full anisotropy control over the whole temperature range from 4 K up to the Curie temperature of the material. The nanobars fabricated from standard in-plane (Ga,Mn)As layers show uniaxial magnetic anisotropy along the long axis of the bar irrespective of their crystal orientation. These results pave the way for new, more complex, semiconductor spintronics devices. Allowing the combination of functional elements of different magnetic anisotropy within the same device, this method can form the basis of novel device schemes relying upon the interaction between their tailored components. We acknowledge financial support from the EU (NANOSPIN FP6-IST-015728).