INSTITUTO DE FISICA LA PLATA
Unidad Ejecutora - UE
congresos y reuniones científicas
Ferromagnetism in Fe-doped rutile TiO2: the role of defects and the long-range magnetic ordering mechanism
A. MUDARRA NAVARRO; C. RODRIGUEZ TORRES; M. WEISSMANN; L. A. ERRICO
Conferencia; Quantum Theory of Solids?, QTS-6; 2014
Departamento defísica, Universidad de Aarhus
Magnetism in wide-gap semiconductors doped with 3d transition elements, usually called dilute magnetic semiconductors (DMS), has become one of the most interesting topics in condensed matter physics. The remarkable volume of experimental and theoretical works shows significant advances in the synthesis and characterization methods. Concerning systems based on semiconducting oxides (O-DMS), most of the efforts were focused on Co and Fe doped TiO2, SnO2, ZnO and In2O3. There is consensus in the scientific community that defects, especially oxygen vacancies, play a fundamental role in the occurrence of ferromagnetic interactions. While bulk samples and thin films of well crystallized and stoichiometric solid solutions of dilute magnetic oxides are mainly paramagnetic, highly defective alloys present room temperature ferromagnetism. Recently a combined theoretical and experimental study enable us to characterize the local structure around transition metal impurities in rutile TiO2 unambiguously and support the conclusion that oxygen vacancies are fundamental for the ferromagnetic response of these systems . In this work we will present an ab ibitio study of Fe-doped rutile TiO2 and SnO2. We explore the role played by oxygen vacancy and electron doping in mediating the magnetic ordering in these systems. We show that two Fe dopants can be stabilized energetically around an oxygen vacancy, and are ferromagnetically coupled to form a bound magnetic polaron. In addition, the combined roles of oxygen vacancy and electron doping in mediating local and nonlocal magnetic ordering is discussed using to different methods to simulate the electron doping: adding electrons to the systems and codoping Fe-TiO2 with donor impurities.  A. Mudarra Navarro, L. A. Errico, C. Rodriguez Torres, A. F. Cabrera, V. Bilovol, M. Rentería and M. Weissmann, Ferromagnetism in transition metal doped rutile TiO2, in Rutile: Properties, Synthesis and Applications". Nova Science, 159-194, 2012.