Ferromagnetism in Co-doped SnO2 film

F. GOLMAR , A.M. MUDARRA NAVARROB, C.E. RODRÍGUEZ TORRESB, F.D. SACCONE, AND F.H. SÁNCHEZ

Buenos Aires, Argentina

Congreso; XV International Symposium on Metastable, Amorphous and nanostructured materials (ISMANAM); 2008

In recent years, the interest for the physical properties of diluted magnetic semiconductors (DMSs) has significantly increased due to their potential technological applications in the field of optoelectronics. Many studies report on high-temperature ferromagnetism in oxide materials such as TM doped anatase (TiO2), zinc oxide (ZnO), and tin dioxide (SnO2) with TM : Co, Ni, Cr, Mn, V, and Fe. SnO2 presents special properties, such as transparency and remarkable chemical and thermal stabilities. Many works reported ferromagnetic properties of TM-doped single crystal SnO2 thin films. Nevertheless, ferromagnetism is much more difficult to find in polycrystalline samples. These controversial observations raise questions about the nature (intrinsic or extrinsic) of ferromagnetism in these systems. This is of particular importance since recent studies on DMS thin films suggested that ferromagnetism could have an extrinsic origin[1]. In this work, we present a study of the magnetic properties of Co doped SnO2 film grown on LaAlO3 single crystal substrate by pulsed laser ablation. While at room temperature the film is ferromagnetic-like with low coercivity (almost zero) at 5 K the coercivity increase to 540 Oe. The magnetization vs temperature curves showed the superposition of paramagnetic and ferromagnetic contributions and an antiferromagnetic transition is observed at about 45 K. The origin of the magnetic hardening of the ferromagnetic component could be related to the apparition of the antiferromagnetic phase.