Fabrication and magnetic characteristic of ferrimagnetic bulk Mn4N

We have successfully fabricated ferrimagnetic bulk Mn4N by doping bulk Mn metal with nitrogen at 900 °C in a flow of NH3/N2 mixture gas. The X-ray diffraction pattern of bulk Mn4N shows a pure Mn4N phase. By magnetic measurements using VSM and SQUID, the hysteresis loop of the bulk Mn4N at 5 and 300 K, together with the M–T curve from 2 to 1000 K at 2 kOe external field is measured. From the 1/χ–T curve, it can be concluded that the sample is ferrimagnet with its Curie temperature around 740 K. The magnetic moment is calculated to be about 0.88 μB/cell at 5 K. The microwave characteristic was investigated by the vector network analyzer in the frequency from 2 to 12 GHz and was fitted by the transmission line theory. We have given the calculated results for the sample thickness of 1.4, 1.5 and 1.9 mm, respectively, by using the electromagnetic parameters of the Mn4N composite. The loss peak shifts to lower frequency with the increasing of composite thickness.