ESR characterization of Zn1-xMnxAl2O4 spinel thin films

M.E. SALETA; R. D. SANCHEZ; O. SHAPOVAL; V. MOSHNYAGA; K. SAMWER

Buenos Aires

Conferencia; At the Frontiers of Condensed Matter IV,; 2008

Tandar

In the geometrically frustrated magnets the spins are located in a well defined lattice, but thegeometric constraints make a simple arrangement of magnetic moments impossible. Recently, these materials have been proposed as good candidates for multiferroic behavior [1]. In the cubic spinel oxides with AB2O4 stoichiometry, the transition metal ions (A and B) are in tetrahedrally and octahedrally coordinated sites respectively. While the ZnAl2O4 is an insulator and non magnetic compound, the MnAl2O4 is a geometrically frustrated magnet. The Mn ions form a geometrically frustrated corner-sharing tetrahedral network (3D). The dominating interaction between the Mn2+ (S=5/2) ions is antiferromagnetic with a Neel temperature of TN=40K [2].We present results of Zn1-xMnxAl2O4 thin films (0<x<1), which were prepared by  metalorganic aerosol deposition technique [3]. The films have been grown epitaxially on MgO(100) substrates and characterized by X-ray diffraction analysis, SEM microscopy and by magnetization and capacitance as a function of temperature and magnetic field. For high x values (x=0.75 and 1), we observed that the magnetization is away from a Curie-Weiss law below 40K, indicating the expecting magnetic ordering of the spinel. At this characteristic temperature we also detected a peak in the capacitance experiments.