High-Resolution Powder Neutron Diffraction on Mn3C

The ground state of Mn3C, a metastable but nonetheless fundamental phase in the context of high-manganese steels, is still a matter of debate, and even the atomic structure of Mn3C has never been refined in the past. Moreover, Mn3C has been described as being nonmagnetic, antiferromagnetic, and also ferrimagnetic. Herein, Mn3C's crystal structure and its magnetic ground state were probed for the first time by high-resolution neutron diffraction between 3.5 and 300 K using well-crystalline samples. Although the neutron-diffraction quality is perfectly able to detect even the magnetic states of the impurities MnO and gamma-Mn, there is no sign of a magnetic ordering for Mn3C down to 3.5 K. Hence, it is justified to characterize Mn3C as paramagnetic at the time being.