Ferromagnetism in ZnO co-doped with Mn and N studied by soft x-ray magnetic circular dichroism

TL;DR

This study investigates the electronic and magnetic properties of Mn- and N-doped ZnO thin films using XMCD and photoemission, revealing coexistence of magnetic states and hybridization effects that influence ferromagnetism.

Contribution

It provides new insights into the electronic structure and magnetic interactions in co-doped ZnO, highlighting the coexistence of different Mn states and hybridization effects.

Findings

Coexistence of paramagnetic and ferromagnetic Mn$^{2+}$ ions in ZnO:Mn,N

Evidence of $p$-$d$ exchange coupling in ZnO:Mn,N

Localized magnetic interactions suggested by spectral weight suppression

Abstract

We have investigated the electronic structure of ZnO:Mn and ZnO:Mn,N thin films using x-ray magnetic circular dichroism (XMCD) and resonance-photoemission spectroscopy. From the Mn 2$p$$\rightarrow3d$ XMCD results, it is shown that, while XMCD signals only due to paramagnetic Mn$^{2+}$ ions were observed in ZnO:Mn, nonmagnetic, paramagnetic and ferromagnetic Mn$^{2+}$ ions coexist in ZnO:Mn,N. XMCD signals of ZnO:Mn,N revealed that the localized Mn$^{2+}$ ground state and Mn$^{2+}$ state hybridized with ligand hole coexisted, implying $p$-$d$ exchange coupling. In the valence-band spectra, spectral weight near the Fermi level was suppressed, suggesting that interaction between magnetic moments in ZnO:Mn,N has localized nature.