Science et Ingénierie des Matériaux et Procédés (SIMaP), INP-Grenoble/CNRS/UJF, BP 75, Saint-Martin d'Hères, France.
Nanotechnology. 2010 Feb 10;21(6):065602. doi: 10.1088/0957-4484/21/6/065602. Epub 2010 Jan 8.
A comparison of the structural and magnetic properties of FePt nanostructures grown at different temperatures on NaCl(001) and MgO(001) substrates is presented. A strong influence of the deposition temperature on the epitaxial growth as well as on the size distribution of FePt nanostructures grown on NaCl substrates is observed. In spite of a large lattice mismatch between FePt and NaCl, a 'cube-over-cube' growth of nanostructures with a narrow size distribution was achieved at 520 K. Moreover, the growth of FePt nanostructures on NaCl(001) is not preceded by the formation of a wetting layer as observed on MgO(001). The higher degree of L1(0) chemical ordering in FePt nanostructures grown on MgO(001) accompanied by the absence of L1(0) variants with an in-plane tetragonal c-axis indicates that the tensile epitaxial stress induced by the MgO substrate is a key factor in the formation of the L1(0) phase with an out-of-plane c-axis. Superparamagnetic behavior is revealed for the FePt nanostructures grown on NaCl(001) due to their small size and relatively poor chemical order.
介绍了在 NaCl(001) 和 MgO(001) 衬底上在不同温度下生长的 FePt 纳米结构的结构和磁性性质的比较。观察到沉积温度对在 NaCl 衬底上生长的 FePt 纳米结构的外延生长以及尺寸分布有很强的影响。尽管 FePt 和 NaCl 之间存在很大的晶格失配，但在 520 K 下仍实现了具有窄尺寸分布的“立方-立方”纳米结构的生长。此外，在 MgO(001) 上观察到的润湿层的形成之前，FePt 纳米结构不在 NaCl(001)上生长。在 MgO(001)上生长的 FePt 纳米结构中 L1(0)化学有序度较高，并且不存在具有面内四方 c 轴的 L1(0)变体，这表明由 MgO 衬底引起的拉伸外延应力是形成具有面外 c 轴的 L1(0)相的关键因素。由于其尺寸较小且化学有序度相对较差，在 NaCl(001)上生长的 FePt 纳米结构表现出超顺磁性行为。
