Absence of ferromagnetism in Co and Mn substituted polycrystalline ZnO
By G. Lawes, A. Risbud, A. P. Ramirez, R. Seshadri. 2004
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We discuss the properties of semiconducting bulk ZnO when substituted with the magnetic transition metal ions Mn and Co, with substituent fraction ranging from $x=0.02$ to $x=0.15$. The magnetic properties were measured as a function of magnetic field and temperature and we find no evidence for magnetic ordering in these systems down to $T=2\phantom{\rule{0.3em}{0ex}}\mathrm{K}$. The magnetization can be fit by the sum of a Curie-Weiss term with a Weiss temperature of $\ensuremath{\Theta}⪢100\phantom{\rule{0.3em}{0ex}}\mathrm{K}$ and a Curie term. We attribute this behavior to contributions from both $t\mathrm{M}$ ions with $t\mathrm{M}$ nearest neighbors and from isolated spins. This particular functional form for the susceptibility is used to explain why no ordering is observed in $t\mathrm{M}$ substituted ZnO samples despite the large values of the Weiss temperature. We also discuss in detail the methods we used to minimize any impurity contributions to the magnetic signal.
Subfields: Condensed Matter Physics, Materials Chemistry
View Paper: https://www.semanticscholar.org/paper/079621251cbc33a2cf348f1a1e64fda3d40bb283
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In Condensed Matter Physics
In Materials Chemistry
Citations in the corpus
- Structure and magnetism of cobalt-doped ZnO thin films (2008, background): “However, others report no ferromagnetism at room temperature [32, 33], or that the observed ferromagnetism originates from metallic cobalt clusters [34, 35].”
- Increase of Mn solubility with decreasing grain size in ZnO (2009, background): “38 19 19 , 39–46 The data are much scarcer in Based on the knowledge that Mn solubility depends on grain and particle size (Figs.”