Impact of post-annealing temperature on the structure, surface topography and magnetic properties of sputtered GdMnO₃ thin films

GdMnO₃ (GMO) thin films were sputtered using an RF Magnetron unit on Quartz substrates. Films post-annealed for 12 h at 750 ℃ and 850 ℃ confirm the orthorhombic structure with pbnm symmetry. The increase in temperature of the films increases their crystallinity and grain size. Raman study substantiates the results of XRD. Annealing at higher temperatures shows a broadening in Raman peaks along with a right shift in the active modes. XPS anlaysis revelas the presense of Mn with Mn³⁺ and Mn⁴⁺ oxidation state. The AFM topography images show increased values in average roughness, root mean square roughness, Kurtosis, skewness and Shannon entropy as a function of rising temperature values. The second-order transition from the incommensurate antiferromagnetic phase to the canted A-type commensurate antiferromagnetic phase is observed. The magnetization value is found to be higher for the film annealed at 850 ℃, whereas the film annealed at 750 ℃ exhibits spin glass behaviour.