Studies of the magnetic properties on Mn-doped GaAs and Zn1-xCoxO thin films / Estudos das propriedades magneticas dos filmes finos de GaAs diopado com Mn e de Zn1-xCoxO




Ferromagnetic semiconductors (FM) are compounds of technological interest due to the possibility of combining their charge and spin degrees of freedom when producing electronic devices. In particular, semiconductor thin films doped with transition metal have become focus of intense scientific investigation since ferromagnetism with reasonably high Curie temperatures (racing from few Kelvin to room temperature) was found in theses films [1-4]. Examples of such dilute magnetic semiconductor (DMS) are Mn-doped GaAs and Co-doped ZnO thin films. ZnO is a direct bandgap II-VI semiconductor with a wurtzite-type structure. In this word, we have performed studies of EPR and magnetic susceptibility in Co-doped ZnO and Mn-doped GaAs thin films in order to further explore the global and local magnetic properties of these intriguing DMS. For the Mn-doped GaAs samples, our results show the absence of ferromagnetic ordering for the amorphous films in the 300 >T >2 K temperature range, in contrast to the ferromagnetism found in crystalline films for TC<110 K. A single EPR line with a temperature independent g-value (g ~ 2) is observed for the amorphous films and the behavior of this ESR linewidth depends on the level of crystallinity of the film. For the Mn-doped GaAs crystalline films, only a ferromagnetic mode is observed for T


paramagnetismo magnetic semiconductors semicondutores magneticos thin films ferromagnetismo paramagnetism ressonancia filmes finos resonance ferromagnetism

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