The electronic structure and atomic magnetic moments of clusters NdFe_6, NdFe_6N_3 and Fe_8 with a dumbbell atom-pair in rare earth-transition element compounds Nd_2Fe_(17)N_ x ( x =0, 3) were studied by spin-polariz...The electronic structure and atomic magnetic moments of clusters NdFe_6, NdFe_6N_3 and Fe_8 with a dumbbell atom-pair in rare earth-transition element compounds Nd_2Fe_(17)N_ x ( x =0, 3) were studied by spin-polarized MS-Xα method. The results are as follows: There are three negative exchange couplings between Fe(c) and Fe(f) atoms in Nd_2Fe_(17), which occur at their odd parity orbitals. Compared to the results of α-Fe calculated by the MS-Xα method, the low Curie temperature of compounds RE_2Fe_(17) can be explained satisfactorily. (2) There is only one weaker negative exchange coupling orbital leaving in between Fe(c) and Fe(f) sites in Nd_2Fe_(17)N_3. These results may be helpful for understanding the effect of interstitial atom M (M=N, H or C) in Fe_2Fe_(17)M_ x on Curie temperature. The other key factors affecting the Fe-Fe exchange coupling in Fe_2Fe_(17) compounds were also discussed.展开更多
The electronic structures and magnetic properties of SmCo7-xMx （M=Ti, Si, Zr, Hf, Cu, B, Ag, Ga, Mn） compounds are investigated by using a spin-polarized MS-Xα method. The results show that the long-range ferromagn...The electronic structures and magnetic properties of SmCo7-xMx （M=Ti, Si, Zr, Hf, Cu, B, Ag, Ga, Mn） compounds are investigated by using a spin-polarized MS-Xα method. The results show that the long-range ferromagnetic order is determined by a stronger 3d-5d interaction, rather than the traditional RKKY interaction, and the effects of doping element M on 3d-5d coupling are negligible in Sm-Co-based compounds. The nonmagnetic dopant Si atoms have a larger effect on the moments of 2e site although they preferably occupy the Co 3g sites, which results in the stronger uniaxial anisotropy of this compound. Analysis of the formation energies indicates that 5d-element doped compounds are more stable than other dopants, and furthermore, they have a higher Curie temperature above room temperature, which will be in favor of their potential application as high-temperature permanent magnets.展开更多
文摘The electronic structure and atomic magnetic moments of clusters NdFe_6, NdFe_6N_3 and Fe_8 with a dumbbell atom-pair in rare earth-transition element compounds Nd_2Fe_(17)N_ x ( x =0, 3) were studied by spin-polarized MS-Xα method. The results are as follows: There are three negative exchange couplings between Fe(c) and Fe(f) atoms in Nd_2Fe_(17), which occur at their odd parity orbitals. Compared to the results of α-Fe calculated by the MS-Xα method, the low Curie temperature of compounds RE_2Fe_(17) can be explained satisfactorily. (2) There is only one weaker negative exchange coupling orbital leaving in between Fe(c) and Fe(f) sites in Nd_2Fe_(17)N_3. These results may be helpful for understanding the effect of interstitial atom M (M=N, H or C) in Fe_2Fe_(17)M_ x on Curie temperature. The other key factors affecting the Fe-Fe exchange coupling in Fe_2Fe_(17) compounds were also discussed.
基金Project supported by the National Natural Science Foundation of China (Grant Nos 10847134 and 60471042)the Natural Science Foundation of Shandong Province, China (Grant No Y2005A05)
文摘The electronic structures and magnetic properties of SmCo7-xMx （M=Ti, Si, Zr, Hf, Cu, B, Ag, Ga, Mn） compounds are investigated by using a spin-polarized MS-Xα method. The results show that the long-range ferromagnetic order is determined by a stronger 3d-5d interaction, rather than the traditional RKKY interaction, and the effects of doping element M on 3d-5d coupling are negligible in Sm-Co-based compounds. The nonmagnetic dopant Si atoms have a larger effect on the moments of 2e site although they preferably occupy the Co 3g sites, which results in the stronger uniaxial anisotropy of this compound. Analysis of the formation energies indicates that 5d-element doped compounds are more stable than other dopants, and furthermore, they have a higher Curie temperature above room temperature, which will be in favor of their potential application as high-temperature permanent magnets.
