Fig 3 - uploaded by Peter Entel
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(a) Spin-up and (b) spin-down Fermi surfaces of the L21-Heusler structure of the stoichiometric Co2NiGa compound. The different colors denote different bands. The -point of the Brillouin zone is at the center and at each corner of the plotted cubes.
Source publication
Advanced magnetic shape memory materials like the prototypical Ni–Mn–Ga alloy system are limited to operating temperatures that are too low for many practical applications. To overcome this problem, an intensive search for new magnetic shape memory compounds has been started. One interesting system, showing magnetic as well as conventional shape me...
Contexts in source publication
Context 1
... planar sheets are present which can be connected by a vector in reciprocal space that corresponds to the q-vector describing the phonon softening [8]. Figure 3 shows the calculated Fermi surfaces of Co 2 NiGa in the conventional Heusler structure for the spin-up and spin-down channels. Since nesting has been commonly discussed in terms of the minority spin-channel for Ni 2 MnGa, the Fermi surface of the minority spin-channel of Co 2 NiGa is also of primary interest, here. ...
Context 2
... nesting has been commonly discussed in terms of the minority spin-channel for Ni 2 MnGa, the Fermi surface of the minority spin-channel of Co 2 NiGa is also of primary interest, here. It is obvious from figure 3 that there is just one extended band (colored in bright orange) primarily located near the zone boundary, that may show small nesting portions while all other bands (small nearly spherical electron or hole pockets) cannot nest. However, as the surface of the bright orange band is small compared to the bands that contribute to the nesting behavior in Ni 2 MnGa, we conclude that nesting in Co 2 NiGa appears strongly suppressed. ...
Context 3
... Fermi surface nesting is therefore not really important in case of Co 2 NiGa, another feature of interest can be extracted from the calculated Fermi surfaces. Checking the contribution of the majority bands to the Fermi surface in figure 3(a) we find that the shape of the surface looks very similar to the case of Ni 2 MnGa. This behavior can be explained by the electronic densities of states of the respective materials. ...
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Citations
Ternary Co–Ni–Sn nanoparticles were prepared using a chemical polyol method, and their magnetic and structural properties were investigated by a vibrating sample magnetometer (VSM), first-order reversal curve (FORC), X-ray diffraction and scanning electron microscopy (SEM). It was found that, by increasing the amount of Sn, the magnetization of the synthesized samples decreased from 65 to 34 emu/g. In addition, the XRD patterns of low Sn concentration samples showed the presence of both CoNi and Sn structures along with a trace of cobalt oxide. However, the crystallinity of the resulting samples decreased to an amorphous state. According to the results of FORC analysis, the soft and hard magnetic phases were completely separated and the percentage of reversibility was reduced due to the increased Sn concentration, so that the percentages of the reversibility and irreversibility were equal in the samples with the highest concentration of Sn. From SEM images, the change in the amount of constituents leads to a morphological variation from spherical-shaped to sheet-like particles.
