| The development of spintronics has attracted ever-increasing interest in recent years because of the potential use of both charge and spin of electrons. The group-IV-based spintronics is extremely appealing, due to high compatibility with mainstream Si-based technology and this has motivated the interests on transition metals doped Si, Ge magnetic semiconductors. At the same time, since the discovery of giant magnetoresistance (MR) from Fe/Cr multilayers, extensive studies of spin-dependent transport properties of Fe, Co-based heterogeneous magnetic structures have been performed for spintronic applications. To sum up, taking into account the potential application of group-IV-based spintronics and the significance of Fe-based heterostructures, the composite structures of Fe, Co and group IV matrix including C, Si, and Ge are designed, and their microstructures, magnetis and magneto-transport properties are compared.The [Co(0.6nm)/Si(xnm)]10 films of different Si layer thicknesses were deposited on glass substrates by magnetron sputtering at room temperature. The volume content of Co in Co/Si films ranged 60-23% by changing the Si layer thickness. It is found that with the Co contents increase, the saturation magnetization of the films were first increased and then decreased. The saturation magnetization of the film which contains 50% Co is biggist, which may be related to the interface diffusion and the formation of the compound betweem Co and Si. From the FC-ZFC, we found that with the decrease of the Co contain, the TB of the Co/Si films disappeared gradually. The TB not appeared in the [Co(0.6nm)/Si(2.0nm)]10 film, it means that Co uniformly doping in the system of Si.The Fe/X (X=C, Si, Ge) films were deposited on glass substrates by magnetron sputtering, and then annealed in vacuum at the annealing temperatures of 400℃, and 600℃, respectively. Their magnetic, transport, and magnetotransport properties of the as-deposited and annealed ones are compared. It is found that the annealing process gives rise to the enhancement of magnetization of the Fe/C films, the increase of the Fe particles size in them, and the reduction of the MR; For Fe/Si films, the annealing process causes the appearance of the Fe particles size, and the enhancement of MR; For Fe/Ge films, the modest annealing temperature such as 400 ℃ cannot influence the magnetization. And no Fe particles can be formed in the films. The unsaturated MR was observed in the as-deposited Fe/Ge film.The [Fe(0.6nm)/Si(1.4nm)]30 films were deposited on different Si substrates by magnetron sputtering at room temperature. It is found that the magnetization of the film of the different substrates were almost unchanged, however, we found room temperature positive MR in the Fe/Si films of the Si substrates.To sum up, the magnetic, transport, and magnetotransport properties of the as-deposited and annealed Co/Si、Fe/X (X=C, Si, Ge) films are discussed and compared. It is found that the various properties are strongly related with the IV group element matrix and the post-annealing process. The saturation magnetization and resistance of Co/Si films can be tuned by the Si layer thickness. At the same structure of the Fe/X (X=C, Si, Ge) films, the saturation magnetization, magnetoresistance and the Fe valence state of the film were related to the annealing temperature and the IV group element. Room temperature positive MR in the Fe/Si films of the Si substrates. Therefore, the microstructures and the properties can be tuned by IV group element matrix and the post-annealing. This work may be beneficial to IV group element-related spintronic research. Moreover, it will pave the way towards the novel spintronics devices with low energy consumption, allowing a seamless integration with electronic circuits. |
PDF Full Text Request