MuSR Investigation and Suppression of TC by overdoped Li in Diluted Ferromagnetic Semiconductor Li1+y(Zn1-xMnx)P

TL;DR

This study uses muon spin relaxation to explore the magnetic properties of Li-doped ferromagnetic semiconductors, revealing how overdoped lithium suppresses ferromagnetism and emphasizing the importance of charge-spin balance.

Contribution

It demonstrates the impact of overdoped lithium on ferromagnetic ordering in Li(Zn,Mn)P, highlighting the delicate balance needed for optimal Curie temperature.

Findings

Overdoping Li suppresses T_C and saturation moments.

Muon spin relaxation confirms nearly 100% magnetic order below T_C.

Static internal field relation aligns with other bulk DFSs.

Abstract

We use muon spin relaxation (muSR) to investigate the magnetic properties of a bulk form diluted ferromagnetic semiconductor (DFS) Li1.15(Zn0.9Mn0.1)P with T_C ~ 22 K. MuSR 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. Li1+y(Zn1-xMnx)P has the advantage of decoupled carrier and spin doping, where Mn2+ substitution for Zn2+ introduces spins and 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.