Upper bound for the s-d exchange integral in n-(Ga,Mn)N:Si from magnetotransport studies

TL;DR

This study uses magnetotransport measurements to establish an upper bound of 40 meV for the s-d exchange integral in n-(Ga,Mn)N:Si, revealing a significantly weaker coupling than in similar II-VI semiconductors, explained by Mn's acceptor role.

Contribution

The paper provides the first magnetotransport-based upper bound for the s-d exchange integral in n-(Ga,Mn)N:Si, highlighting differences with II-VI semiconductors and proposing a theoretical explanation.

Findings

N0α < 40 meV for n-(Ga,Mn)N:Si

s-d coupling is at least 5 times weaker than in n-(Zn,Mn)O

Weak localization sensitivity reveals exchange interaction magnitude

Abstract

A series of recent magnetooptical studies pointed to contradicting values of the s-d exchange energy N0{\alpha} in Mn-doped GaAs and GaN as well as in Fe-doped GaN. Here, a strong sensitivity of weak-localization phenomena to symmetry breaking perturbations (such as spin-splitting and spin-disorder scattering) is exploited to evaluate the magnitude of N0{\alpha} for n-type wurtzite (Ga,Mn)N:Si films grown by metalorganic vapor phase epitaxy. Millikelvin magnetoresistance studies and their quantitative interpretation point to N0{\alpha} < 40 meV, a value at least 5 times smaller than the one found with similar measurements on, e.g., $n$-(Zn,Mn)O. It is shown that this striking difference in the values of the s-d coupling between $n$-type III-V and II-VI dilute magnetic semiconductors can be explained by a theory that takes into account the acceptor character of Mn in III-V compounds.