Revealing a masked Verwey transition in nanoparticles of coexisting Fe-oxide phases.

The attractive electronic and magnetic properties together with their biocompatibility make iron-oxide nanoparticles appear as functional materials. In Fe-oxide nanoparticle (IONP) ensembles, it is crucial to enhance their performance thanks to controlled size, shape, and stoichiometry ensembles. In light of this, we conduct a comprehensive investigation in an ensemble of ca. 28 nm cuboid-shaped IONPs in which all the analyses concur with the coexistence of magnetite/maghemite phases in their cores. Here, we are disclosing the Verwey transition by temperature dependent (4-210 K) Raman spectroscopy.