Structural and magnetic properties of antiperovskite Mn3NiNx thin films

Influence of nitrogen fractions[Nf=N2/(N2+Ar2)] on the structural and magnetic properties of Mn3NiNx thin films prepared on quartz substrates using magnetron sputtering have been studied. The N/Ni ratio increased (N/Ni=0.3-1.1) while the peak (200) shifted to lower angles with increasing Nf. It revealed that there was significant variation in the preferred orientation and Néel temperature (TN) for the films with increasing Nf. Strong indication for a frozen state is found, determined from the difference between field-cooled and zero-field-cooled magnetizations. The ac susceptibility measurements show a peak position shifting as a function of the driving frequency f and magnetization value does not saturate in the field range. These findings consistently demonstrate that Mn3NiNx thin films exhibit a spin-glass state at low temperature.