Studies of the effective magnetic anisotropy in GaMnAs as a function of the Mn implantation energy.

E. DE BIASI; M. A. A. PUDENZI; R. DOBRZANSKI; M. BEHAR; M. KNOBEL; J. BETTINI

Buenos Aires

Congreso; FCM IV Current Trends and Novel Materials; 2008

Magnetic semiconductors have a variety of applications in storage and data processing. In particular, GaAs can exhibit magnetic properties when doped with Mn, either by epitaxial growth or ion implantation. There are discrepancies in literature related to the orientation of the easy axis of magnetization in this type of system, probably due to variations in growth parameters or sample preparation as temperature and annealing time. In this work, Mn and As ions were co-implanted on semi-insulating GaAs substrates, keeping the Mn and As dose equal in all samples. The As implantation energy was the same but, as a main parameter for comparative analysis, the Mn energy were varied for each sample. Rapid thermal annealing (RTA) was done at 750°C. Magnetic measurements were made using a commercial SQUID magnetometer.We have analyzed the dependence of the effective anisotropy regarding the Mn implantation energy. Hysteresis cycles have shown that sample magnetization depends on the crystallographic direction, changing the effective easy axes orientation. TEM measurements help us to understand some of the magnetic behavior. (Supported by: CNPq and FAPESP).