Exposure of the Hidden Anti-Ferromagnetism in Paramagnetic CdSe:Mn Nanocrystals

TL;DR

This paper combines theoretical and experimental methods, including group theory analysis, to uncover hidden anti-ferromagnetic interactions in paramagnetic CdSe:Mn nanocrystals, revealing detailed magnetic behaviors and ion aggregation effects.

Contribution

It introduces a novel analysis approach using group theory to distinguish anti-ferromagnetic interactions from overall paramagnetism in doped nanocrystals.

Findings

Identified signatures of anti-ferromagnetism in magnetization data

Determined the average number of Mn2+ ions in nanocrystals

Estimated the fraction of aggregative Mn2+ ions

Abstract

We present theoretical and experimental investigations of the magnetism of paramagnetic semiconductor CdSe:Mn nanocrystals and propose an efficient approach to the exposure and analysis of the underlying anti-ferromagnetic interactions between magnetic ions therein. A key advance made here is the build-up of an analysis method with the exploitation of group theory technique that allows us to distinguish the anti-ferromagnetic interactions between aggregative Mn2+ ions from the overall pronounced paramagnetism of magnetic ion doped semiconductor nanocrystals. By using the method, we clearly reveal and identify the signatures of anti-ferromagnetism from the measured temperature dependent magnetisms, and furthermore determine the average number of Mn2+ ions and the fraction of aggregative ones in the measured CdSe:Mn nanocrystals.