Probing the Hidden Order in URu$_2$Si$_2$ by Impurity Doping

URu$_2$Si$_2$ exhibits a clear broken symmetry ground state at 17.5 K, but the nature of the order parameter has not been known for more than two decades. Motivated by the fact that Rh doping in this compound induces antiferromagnetism, indicating that the hidden order is closely related with the antiferromagnetism, we studied $^{29}$Si NMR with varying Rh concentration. This $^{29}$Si NMR study reveals that the antiferromagnetism arises from the local suppression of the hidden order by Rh doping. We propose that the antiferromagnetism emerges as a result of the local suppression of the hidden order yet only within the long range hidden order phase.