Garnero Cyril, Pierrot Alexandre, Gatel Christophe, Marcelot Cécile, Arenal Raul, Florea Ileana, Bernand-Mantel Anne, Soulantica Katerina, Poveda Patrick, Chaudret Bruno, Blon Thomas, Lacroix Lise-Marie
Université de Toulouse, UMR 5215 INSA, CNRS, UPS, Laboratoire de Physique et Chimie des Nano-Objets, 135 avenue de Rangueil, F-31077 cedex 4 Toulouse, France.
Centre d'Elaboration de Matériaux et d'Etudes Structurales, CEMES-CNRS, 29 rue Jeanne Marvig, 31055 Toulouse, France.
Nano Lett. 2021 Apr 28;21(8):3664-3670. doi: 10.1021/acs.nanolett.1c01087. Epub 2021 Apr 13.
Single crystalline magnetic FeCo nanostars were prepared using an organometallic approach under mild conditions. The fine-tuning of the experimental conditions allowed the direct synthesis of these nano-octopods with body-centered cubic () structure through a one-pot reaction, contrarily to the seed-mediated growth classically used. The FeCo nanostars consist of 8 tetrahedrons exposing {311} facets, as revealed by high resolution transmission electron microscopy (HRTEM) imaging and electron tomography (ET), and exhibit a high magnetization comparable with the bulk one ( = 235 A·m·kg). Complex 3D spin configurations resulting from the competition between dipolar and exchange interactions are revealed by electron holography. This spin structures are stabilized by the high aspect ratio tetrahedral branches of the nanostars, as confirmed by micromagnetic simulations. This illustrates how magnetic properties can be significantly tuned by nanoscale shape control.
采用有机金属方法在温和条件下制备了单晶磁性FeCo纳米星。与传统的种子介导生长方法不同，通过微调实验条件，可以通过一锅法直接合成具有体心立方（）结构的这些纳米八足体。高分辨率透射电子显微镜（HRTEM）成像和电子断层扫描（ET）显示，FeCo纳米星由8个暴露{311}面的四面体组成，并且具有与块状材料相当的高磁化强度（= 235 A·m·kg）。电子全息术揭示了由偶极相互作用和交换相互作用之间的竞争产生的复杂三维自旋构型。微磁模拟证实，这种自旋结构通过纳米星的高纵横比四面体分支得以稳定。这说明了如何通过纳米尺度的形状控制来显著调节磁性。
