Vacancy-driven non-cubic local structure and magnetic anisotropy tailoring in Fe$_x$O-Fe$_{3-\delta}$O$_4$ nanocrystals
| Autor: | Lappas, Alexandros, Antonaropoulos, George, Brintakis, Konstantinos, Vasilakaki, Marianna, Trohidou, Kalliopi N., Iannotti, Vincenzo, Ausanio, Giovanni, Kostopoulou, Athanasia, Abeykoon, Milinda, Robinson, Ian K., Bozin, Emil S. |
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| Rok vydání: | 2020 |
| Předmět: | |
| Zdroj: | Phys. Rev. X 9, 041044 (2019) |
| Druh dokumentu: | Working Paper |
| DOI: | 10.1103/PhysRevX.9.041044 |
| Popis: | 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. Comment: 20 pages, 9 figures, Supplemental Material |
| Databáze: | arXiv |
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