Jianping Wang, a physicist at the University of Minnesota, created the compound, but he's actually not the first to do so:
In 1996, researchers from the Central Research Laboratory of Hitachi in Japan made the same iron and nitrogen compound. Their research also showed that the material exceeded limitations set by traditional theories. However, scientists were unable to duplicate their experiments.
Apparently Wang has "taken special care to allow other scientists to duplicate his experimental setup" because of these failed attempts of the past. It's a shame that his experiment doesn't count as proof of the original compound's creation for some reason though.