Vacancy-driven non-cubic local structure and magnetic anisotropy tailoring in Fe${}_x$O-Fe${}_{3-\delta }$O${}_4$ nanocrystals

Abstract

In contrast to bulk materials, nanoscale crystal growth is critically influenced by size- and shape-dependent properties. However, it is challenging to decipher how stoichiometry, in the realm of mixed-valence elements, can act to control physical properties, especially when complex bonding is implicated by short and long-range ordering of structural defects. Here, solution-grown iron-oxide nanocrystals (NCs) of the pilot wustite system are found to convert into iron-deficient rock-salt and ferro-spinel sub-domains, but attain a surprising tetragonally distorted local structure. Cationic vacancies within chemically uniform NCs are portrayed as the parameter to tweak the underlying properties. These lattice imperfections are shown to produce local exchange-anisotropy fields that reinforce the nanoparticles magnetization and overcome the influence of finite-size effects. The concept of atomic-scale defect control in subcritical size NCs, aspires to become a pathway to tailor-made properties with improved performance for hyperthermia heating over defect-free NCs.

arXiv comment20 pages, 9 figures, Supplemental Material

References in corpus (4)

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• Jahn-Teller distortion driven magnetic polarons in magnetite
• Colloidal Anisotropic ZnO-Fe@FexOy Nanoarchitectures with Interface-Mediated Exchange-Bias and Band-Edge Ultraviolet Fluorescence
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Cited by in corpus (4)

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