We use muon spin relaxation $\left(\mu \mathrm{SR}\right)$ to investigate the magnetic properties of a bulk form diluted ferromagnetic semiconductor (DFS) ${\mathrm{Li}}_{1.15}({\mathrm{Zn}}_{0.9}\mathrm{Mn}{}_{0.1})\mathrm{P}$ with $T_C\sim 22$ K. $\mu \mathrm{SR}$ results confirm the gradual development of ferromagnetic ordering below $T_C$ with a nearly 100% magnetic ordered volume. Despite its low carrier density, the relation between static internal field and Curie temperature observed for Li(Zn,Mn)P is consistent with the trend found in (Ga,Mn)As and other bulk DFSs, indicating these systems share a common mechanism for the ferromagnetic exchange interaction. ${\mathrm{Li}}_{1+y}\left({\mathrm{Zn}}_{1-x}{\mathrm{Mn}}_x\right)\mathrm{P}$ has the advantage of decoupled carrier and spin doping, where ${\mathrm{Mn}}^{2+}$ substitution for ${\mathrm{Zn}}^{2+}$ introduces spins and ${\mathrm{Li}}^{+}$ off-stoichiometry provides carriers. This advantage enables us to investigate the influence of overdoped Li on the ferromagnetic ordered state. Overdoping Li suppresses both $T_C$ and saturation moments for a certain amount of spins, which indicates that more carriers are detrimental to the ferromagnetic exchange interaction, and that a delicate balance between charge and spin densities is required to achieve highest $T_C$.

• Received 24 April 2014
• Revised 14 June 2014

DOI:https://doi.org/10.1103/PhysRevB.90.085123