Annealing effects on the microstructure and properties of Y(Ni,Mn)O3 thin films

Epitaxially c-axis oriented thin films of YNixMn1−xO3 (YNMO), x = 0.33 and 0.5, were grown on (1 0 0) SrTiO3 substrates by pulsed laser-ablated deposition technique. High temperature oxygen annealing shows a large improvement in the ferromagnetic transition temperature Tc for the film with x(Ni) = 0.33 while only a slight increase in Tc occurs for the x(Ni) = 0.5 film. We suggest that such increase in Tc is largely associated with microstructural changes induced by the thermal annealing. In order to optimize the magnetic properties of the YNMO films, it is necessary to control the initial growth conditions so as to have a microstructure of well-connected grains of uniform size.