Thermally-induced co-existence of superparamagnetism and spin-glass like behavior in undoped amorphous AlN thin film

•Nitrogen (N) vacancies present in AlN confirmed by EDX, XPS and RBS measurements.•Spin glass phase emerged after vacuum annealing of AlN film at 850 °C for 4 h.•N vacancy mediated Superparamagnetism (SPM) and spin glass (SG) state in AlN film.•The estimated Curie temperature is ∼ 775 K which is very high for un-doped AlN.•Magnetic volume increases from 3.6 to 6.1%, after vacuum annealing of AlN film.