Excitonic giant Zeeman effect in GaN:Mn^3+

TL;DR

This paper reports the direct observation of excitonic giant Zeeman splitting in GaN:Mn^3+, revealing strong exchange interactions and a rare ferromagnetic coupling between magnetic ions and holes in a wide-gap semiconductor.

Contribution

It provides the first direct measurement of excitonic Zeeman splitting in (Ga,Mn)N and determines the exchange integrals, highlighting a rare ferromagnetic interaction.

Findings

Observation of excitonic giant Zeeman splitting in GaN:Mn^3+

Determination of exchange integral difference N_0(alpha-beta)=-1.2 eV

Identification of ferromagnetic interaction between Mn^3+ ions and holes

Abstract

We describe a direct observation of the excitonic giant Zeeman splitting in (Ga,Mn)N, a wide-gap III-V diluted magnetic semiconductor. Reflectivity and absorption spectra measured at low temperatures display the A and B excitons, with a shift under magnetic field due to s,p-d exchange interactions. Using an excitonic model, we determine the difference of exchange integrals between Mn^3+ and free carriers in GaN, N_0(alpha-beta)=-1.2 +/- 0.2 eV. Assuming a reasonable value of alpha, this implies a positive sign of beta which corresponds to a rarely observed ferromagnetic interaction between the magnetic ions and the holes.