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arXiv · 1610.04263

Nanoscale distribution of magnetic anisotropies in bimagnetic soft core-hard shell MnFe$_2$O$_4$@CoFe$_2$O$_4$ nanoparticles

Niéli Daffé·Marcin Sikora·Mauro Rovezzi·Nadejda Bouldi·Véronica Gavrilov·Sophie Neveu·Fadi Choueikani·Philippe Ohresser·Vincent Dupuis·Dario Taverna·Alexandre Gloter·Marie-Anne Arrio·Philippe Sainctavit·Amélie Juhin
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Abstract

The nanoscale distribution of magnetic anisotropies was measured in core@shell MnFe$_2$O$_4$@CoFe$_2$O$_4$ 7.0 nm particles using a combination of element selective magnetic spectroscopies with different probing depths. As this picture is not accessible by any other technique, emergent magnetic properties were revealed. The coercive field is not constant in a whole nanospinel. The very thin (0.5 nm) CoFe$_2$O$_4$ hard shell imposes a strong magnetic anisotropy to the otherwise very soft MnFe$_2$O$_4$ core: a large gradient in coercivity was measured inside the MnFe$_2$O$_4$ core with lower values close to the interface region, while the inner core presents a substantial coercive field (0.54 T) and a very high remnant magnetization (90% of the magnetization at saturation).

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Niéli Daffé, Marcin Sikora, Mauro Rovezzi, Nadejda Bouldi, Véronica Gavrilov, Sophie Neveu, Fadi Choueikani, Philippe Ohresser, Vincent Dupuis, Dario Taverna, Alexandre Gloter, Marie-Anne Arrio, Philippe Sainctavit, Amélie Juhin. 2017-09-14. Nanoscale distribution of magnetic anisotropies in bimagnetic soft core-hard shell MnFe$_2$O$_4$@CoFe$_2$O$_4$ nanoparticles. https://doi.org/10.1002/admi.201700599

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