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.This work was supported by EU FP7 604448 (NanoMag) andMAT2017-83631-C3-R. Dr Norbert Schell is acknowledged forthe time at the HEMS beamline, and J. F. thanks MUDP (MST141-01415).