I have searched in my databese (FIND-IT) but the cif files of Mn4N refer only to the Pm-3m structure, no files are present in which there is the P-43m crystal structure. Are you sure of this information?
Thank you! I know there are two crystal structures with space groups of P m-3m and P-43m for this compound and the one I have in XRD pattern does not match with P m-3m
PDF-2 database really contains an entry for Mn4N with the P-43m space group (00-001-1202), but it seems to be the result of the incorrect indexing. Lattice parameters are the same as for Pm-3m and authors of that report observed only 5 main peaks of their sample. Did you try to check for other manganese nitrides (Mn3N2 etc.)?
In general the first place to search for cif files (with no issues of access) is COD - the Crystallography Open Database. Currently there are 302604 entries in the COD.On this occasion the database does not contain Mn4N but does include Mn2N0.86/ MnN0.43