Ferromagnetism in transition-metal-doped semiconducting oxide thin films

A rather complete work on transition-metal (TM)-doped TiO2 thin films has been done and room ferromagnetism (FM) is found in the whole series of Sc/V/Cr/Mn/Fe/Co/Ni-doped TiO2 films. Not only is it remarkable that for the first time, FM at high temperature was achieved in TM-doped TiO2, but also a very big magnetic moment of 4.2 mu(B)/atom could be obtained, and direct evidences of real ferromagnets with big domains were shown as well. A similar chemical trend was achieved in TM-doped In2O3 films, however, the observed magnetic moment is rather modest, with the maximal value is of only 0.71 mu(B)/atom for Ni-doped In2O3 films. As regards TM-doped SnO2 films, observed magnetic moments could be very large, with the maximum saturation of 6 mu(B) per impurity atom for Cr-doped SnO2 thin films, but it could be influenced very much depending on substrate types. On the other hand, results on TM-doped ZnO films interestingly have revealed that in these systems, the magnetism more likely resulted from defects and/or oxygen vacancies. (C) 2006 Elsevier B.V. All rights reserved.