@article{8866fab8ce274033be886d311ecd9489,
title = "Magnetic properties of Fe/Cu codoped ZnO nanocrystals",
abstract = "Free-standing ZnO nanocrystals simultaneously doped with Fe and Cu with varying Fe/Cu compositions have been synthesized using colloidal methods with a mean size of ∼7.7 nm. Interestingly, while the Cu-doped ZnO nanocrystal remains diamagnetic and Fe-doped samples show antiferromagnetic interactions between Fe sites without any magnetic ordering down to the lowest temperature investigated, samples doped simultaneously with Fe and Cu show a qualitative departure in exhibiting ferromagnetic interactions, with suggestions of ferromagnetic order at low temperature. XAS measurements establish the presence of Fe 2+ and Fe 3+ ions, with the concentration of the trivalent species increasing in the presence of Cu doping, providing direct evidence of the Fe 2+ + Cu 2+ ⇌ Fe 3+ + Cu + redox couple being correlated with the ferromagnetic property. Using DFT, the unexpected ferromagnetic nature of these systems is explained in terms of a double exchange between Fe atoms, mediated by the Cu atom, in agreement with experimental observations.",
author = "Ranjani Viswanatha and Doron Naveh and Chelikowsky, {James R.} and Leeor Kronik and Sarma, {D. D.}",
note = "Department of Science and Technology, Government of India; International Centre for Theoretical Physics and Department of Science and Technology; Minerva Foundation; Lise Meitner Minerva Center for Computational Chemistry; historical generosity of the Perlman family; U.S. Department of Energy, Office of Basic Energy Sciences and Office of Advanced Scientific Computing Research [DE-FG02-06ER46286, DE-SC0001878]; Texas Advanced Computing Center (TACC) [TG-DMR090026]Work in Bangalore was supported by the Department of Science and Technology, Government of India. RV. and D.D.S. acknowledge the support of the International Centre for Theoretical Physics and Department of Science and Technology under their Users Programs for Synchrotron Radiation. RN. and D.D.S. thank Debangshu Chaudhuri, Sameer Sapra and the beamline scientists at the BEAR beamline of Elettra, Trieste for help with the X-ray absorption study. Work in Rehovoth was supported by the Minerva Foundation, the Lise Meitner Minerva Center for Computational Chemistry, and the historical generosity of the Perlman family. Work in Texas was supported by the U.S. Department of Energy, Office of Basic Energy Sciences and Office of Advanced Scientific Computing Research (Grant No. DE-FG02-06ER46286 on nanostructures and Grant No. DE-SC0001878 on oxides). Computational resources were provided by National Energy Research Scientific Computing Center (NERSC) and the Texas Advanced Computing Center (TACC) under Grant TG-DMR090026.",
year = "2012",
month = aug,
day = "2",
doi = "10.1021/jz300741z",
language = "الإنجليزيّة",
volume = "3",
pages = "2009--2014",
journal = "Journal of Physical Chemistry Letters",
issn = "1948-7185",
publisher = "American Chemical Society",
number = "15",
}