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

Shou-Jyun Zou , Sheng-Tsung Wang , Ming-Fan Wu , Wen-Bin Jian , and Shun-Jen Cheng *


Department of Electrophysics, National Chiao Tung University, Hsinchu 300, Taiwan

ACS Nano, 2015, 9 (1), pp 503–511

DOI: 10.1021/nn5056892

Publication Date (Web): December 31, 2014

Copyright © 2014 American Chemical Society

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 development 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.

Keywords: anti-ferromagnetism; paramagnetism; magnetic semiconductor nanocrystals; CdSe; Mn

http://pubs.acs.org/doi/abs/10.1021/nn5056892