When magnetic ions such as $Mn^{2+}$, $Cr^{2+}$ and $Fe^{2+}$ are substituted into nonmagnetic semiconductors these materials have the properties of both semiconductors and ferromagnets, so which are called diluted magnetic semiconductors (DMS). Only a few of them, however, exhibits room temperature ferromagnetism which is needed for the practical applications.
Recently, a new ferromagnetic semiconductor $(ZnMn)GeP_2$ is discovered, presents room temperature ferromagnetism, $T_C=312K$, and anti ferromagnetism below 40K. But such a behavior of magnetic phase is almost same as that of manganese phosphide, MnP, so there has been a controversy about the existence of MnP cluster in $(ZnMn)GeP_2$. Therefore it is necessary to verify whether the $(ZnMn)GeP_2$ is a real DMS or not.
It is discovered by nuclear magnetic resonance experiment of P in 7.1T, that the central frequency shift of spectrum is proportional to M vs. T curve and that the local field at P nucleus which makes the frequency shift has opposite direction to magnetization. These results shows that this local field can be considered as transferred hyperfine field like in usual ferromagnets and it means the cluster effect is very weak in $(ZnMn)GeP_2$.
