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A schematic illustration of the gas-aggregation-type cluster-deposition method used for the growth of HfCo7 nanoparticles.
(a) X-ray diffraction patterns of bulk HfCo7 and unaligned HfCo7 nanoparticles (NPs), where the estimated XRD peak positions corresponding to the orthorhombic structure using TOPAS are shown as black-dotted vertical lines. (b) Transmission electron microscope image of NPs. The corresponding particle-size histogram is given as an inset, where σ and d are the standard deviation and average particle size, respectively.
(a) M-H curves of the unaligned HfCo7 NPs measured at 10 K and 300 K and bulk alloy measured at 300 K. (b) An estimation of magnetic anisotropy constant K1 from the high-field region of M vs. H curves using the law of approach to saturation method (see Refs. 1222–24). The solid spheres and lines represent the corresponding experimental data and fitting, respectively.
The unaligned exchanged-coupled HfCo7:Fe-Co nanocomposites with different volume fractions (vol. %) of soft Fe-Co phase: (a) X-ray diffraction patterns, where the red and green-dotted vertical lines represent the standard positions of diffraction peaks corresponding to HfCo7 and Fe-Co, respectively. (b) The expanded room-temperature M-H curves.
Easy-axis alignment of HfCo7 nanoparticles (NPs): (a) Schematic illustration of the alignment method using a set of permanent magnets (NS), prior to deposition on substrate, where the sputtering guns used for depositing Fe-Co soft phase and cap layer are not shown here. (b) Three dimensional view of the substrate is also given—in order to show the direction of the applied magnetic field (x-axis) used for alignment with respect to the substrate plane. The expanded room-temperature M-H curves of the aligned NPs measured along the easy (x-axis) and hard (y-axis) directions for (c) HfCo7 NPS and (d) HfCo7:Fe-Co nanocomposites with 18 vol. % of Fe-Co, whereas the M-H curves for the corresponding unaligned samples also are given for comparison.
Comparison of Hc and Mr /Ms at 300 K measured along easy (x-axis) and hard (y-axis) directions of the magnetically aligned HfCo7 nanoparticles and HfCo7:Fe-Co nanocomposites.
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