[FePt/Ag]n multilayers were deposited on glass substrates by RF magnetron sputtering and ex situ annealed at 550℃ for 30 min. The effects of inserted Ag layer thickness and the number of bilayer repetitions （n） on ...[FePt/Ag]n multilayers were deposited on glass substrates by RF magnetron sputtering and ex situ annealed at 550℃ for 30 min. The effects of inserted Ag layer thickness and the number of bilayer repetitions （n） on the structure and magnetic properties of the multilayers were investigated. It was found that the difference between in-plane and out-of-plane coercivities varied with an increase of inserted Ag layer thickness in the [FePt 2 nm/Ag x nm]10 multilayers. The ratio of out-of-plane coercivity to in-plane coercivity reached the maximum value with the Ag layer thickness of 5 nm, indicating that the Ag layer thickness plays an important role in obtaining perpendicular orientation. For the [FePt 2 nm/Ag 5 um]n multilayers, perpendicular orientation is also influenced by n. The maximum value of the ratio of out-of-plane coercivity to in-plane coercivity appeared when n was given as 8. It was found that the [FePt 2 nm/Ag 5 nm]8 had a high perpendicular coercivity of 520 kA/m and a low in-plane one of 88 kA/m, which shows a strong perpendicular anisotropy.展开更多
FePt/Ag thin films were deposited by magnetron sputtering onto 7059 glass substrates, then were annealed at 550 ℃ for 30 min. Nanostructured FePt/Ag films were successfully obtained with the magnetic easy axis of L10...FePt/Ag thin films were deposited by magnetron sputtering onto 7059 glass substrates, then were annealed at 550 ℃ for 30 min. Nanostructured FePt/Ag films were successfully obtained with the magnetic easy axis of L10 FePt perpendicular to the film plane. It was found that the development of （001） texture depended strongly on the thicknesses of FePt magnetic layer and Ag underlayer. The L10 ordered FePt（15 nm）/Ag（50 nm） with （001） orientation can be obtained. And the perpendicular coercivity of FePt（15 nm）/Ag（50 nm） film reached to 7.2× 10^5 A/m, whereas the longitudinal one was only 3.2×10^4 A/m. The non-magnetic Ag underlayer can not only induce （001） orientation and ordering of FePt grains, but also reduce the intergrain interactions.展开更多
FePt/Ag)n nano-multilayers were deposited on MgO(100) single crystal with laser ablation and then sub-jected to annealing. FePt L10 grains with (001) texture and a large perpendicular magnetic anisotropy constant Ku o...FePt/Ag)n nano-multilayers were deposited on MgO(100) single crystal with laser ablation and then sub-jected to annealing. FePt L10 grains with (001) texture and a large perpendicular magnetic anisotropy constant Ku of the order of 106 J/m3 were formed. A thick Ag layer is found to be favorable for improving the (111) preferential orientation and decreasing the dispersion of the easy axis for magnetiza-tion. The measurement of time decay of magnetization gave rise to an activation volume as small as 6×10-25 m3, showing the promising perspective of being the recording medium for future high density perpendicular recording.展开更多
FePt/Ag]10 multilayers were deposited on glass substrates by magnetron sputtering. After being annealed at 550℃ for 30 min, the coercivities of [FePt/Ag]10 multilayer films were observably improved. Magnetic properti...FePt/Ag]10 multilayers were deposited on glass substrates by magnetron sputtering. After being annealed at 550℃ for 30 min, the coercivities of [FePt/Ag]10 multilayer films were observably improved. Magnetic properties of [FePt/Ag]10multilayer films are influenced by the Ag content. The highest coercivity is obtained for those multilayer films that the Ag content is about 25%. The analysis for the re- manence curves shows that the lower FePt layer thickness is favorable for decreasing the intergranular interaction. Re- sult of XRD shows that a thick Ag layer can enhance the intensity of FePt(001) peak. A magnetic activation volume of the order of 10?24 m3 is obtained by the measurement of magnetic viscosity, showing that it is promising to be ultra- high density recording media.展开更多
FePt thin films and [FePt/Ag]n multilayer thin films were prepared by magnetron sputtering technique and subsequent annealing process. By comparing the microstructure and magnetic properties of these two kinds of thin...FePt thin films and [FePt/Ag]n multilayer thin films were prepared by magnetron sputtering technique and subsequent annealing process. By comparing the microstructure and magnetic properties of these two kinds of thin films, effects of Ag addition on the structure and properties of FePt thin films were investigated. Proper Ag addition was found helpful for FePt phase transition at lower annealing temperature. With Ag addition, the magnetic domain pattern of FePt thin film changed from maze-like pattern to more discrete island-like domain pattern in [FePt/Ag]n multilayer thin films. In addition, introducing nonmagnetic Ag hindered FePt grains from growing larger. The in-depth defects in FePt films and [FePt/Ag]n multilayer films verify that Ag addition is attributed to a large number of pinning site defects in [FePt/Ag]n film and therefore has effects on its magnetic properties and microstructure.展开更多
L10 FePt nanocomposite with high magnetocrystalline anisotropy energy has been extensively investigated in the fields of ultra-high density magnetic recording media. However, the order-disorder transition temperature ...L10 FePt nanocomposite with high magnetocrystalline anisotropy energy has been extensively investigated in the fields of ultra-high density magnetic recording media. However, the order-disorder transition temperature of the nanocom- posite is higher than 600 ℃, which is a disadvantage for the use of the material due to the sustained growth of FePt grain under the temperature. To address the problem, addition of Ag atoms has been proposed, but the magnetic properties of the doped system are still unclear so far. Here in this paper, we use first-principles method to study the lattice parameters, formation energy, electronic structure, atomic magnetic moment and order-disorder transition temperature of L 10 FePt with Ag atom doping. The results show that the formation energy of a Ag atom substituting for a Pt site is 1.309 eV, which is lower than that of substituting for an Fe site 1.346 eV. The formation energy of substituting for the two nearest Pt sites is 2.560 eV lower than that of substituting for the further sites 2.621 eV, which indicates that Ag dopants tend to segregate L10 FePt. The special quasirandom structures （SQSs） for the pure FePt and the FePt doped with two Ag atoms at the stable Pt sites show that the order-disorder transition temperatures are 1377 ℃ and 600 ℃, respectively, suggesting that the transition temperature can be reduced with Ag atom, and therefore the FePt grain growth is suppressed. The satura- tion magnetizations of the pure FePt and the two Ag atoms doped FePt are 1083 emu/cc and 1062 emu/cc, respectively, indicating that the magnetic property of the doped system is almost unchanged.展开更多
[AIN/FePt]10, [AIN/FePt]10/Ag and Ag/[AIN/FePt]10 thin films were deposited by magnetron sputtering onto 7059 glass substrates, then were annealed at 550℃ for 30 min. It is found that introducing non-magnetic Ag unde...[AIN/FePt]10, [AIN/FePt]10/Ag and Ag/[AIN/FePt]10 thin films were deposited by magnetron sputtering onto 7059 glass substrates, then were annealed at 550℃ for 30 min. It is found that introducing non-magnetic Ag underlayer can improve the ordering and （001） preferred orientation of FePt grains. Furthermore, the （001） texture of FePt grains increases with increasing Ag underlayer thickness. However, with Ag top layer given, it can only be observed that the ordering of FePt grains was promoted.展开更多
基金This work is financially supported by the National Natural Science Foundation of China (No. 10574085) Natural Science Foundation ofShanxi Province, China (No. 20041032).
文摘[FePt/Ag]n multilayers were deposited on glass substrates by RF magnetron sputtering and ex situ annealed at 550℃ for 30 min. The effects of inserted Ag layer thickness and the number of bilayer repetitions （n） on the structure and magnetic properties of the multilayers were investigated. It was found that the difference between in-plane and out-of-plane coercivities varied with an increase of inserted Ag layer thickness in the [FePt 2 nm/Ag x nm]10 multilayers. The ratio of out-of-plane coercivity to in-plane coercivity reached the maximum value with the Ag layer thickness of 5 nm, indicating that the Ag layer thickness plays an important role in obtaining perpendicular orientation. For the [FePt 2 nm/Ag 5 um]n multilayers, perpendicular orientation is also influenced by n. The maximum value of the ratio of out-of-plane coercivity to in-plane coercivity appeared when n was given as 8. It was found that the [FePt 2 nm/Ag 5 nm]8 had a high perpendicular coercivity of 520 kA/m and a low in-plane one of 88 kA/m, which shows a strong perpendicular anisotropy.
文摘FePt/Ag thin films were deposited by magnetron sputtering onto 7059 glass substrates, then were annealed at 550 ℃ for 30 min. Nanostructured FePt/Ag films were successfully obtained with the magnetic easy axis of L10 FePt perpendicular to the film plane. It was found that the development of （001） texture depended strongly on the thicknesses of FePt magnetic layer and Ag underlayer. The L10 ordered FePt（15 nm）/Ag（50 nm） with （001） orientation can be obtained. And the perpendicular coercivity of FePt（15 nm）/Ag（50 nm） film reached to 7.2× 10^5 A/m, whereas the longitudinal one was only 3.2×10^4 A/m. The non-magnetic Ag underlayer can not only induce （001） orientation and ordering of FePt grains, but also reduce the intergrain interactions.
基金supported by the Scientific Research Foundation for returned overseas Chinese scholars of State Education Ministry
文摘FePt/Ag)n nano-multilayers were deposited on MgO(100) single crystal with laser ablation and then sub-jected to annealing. FePt L10 grains with (001) texture and a large perpendicular magnetic anisotropy constant Ku of the order of 106 J/m3 were formed. A thick Ag layer is found to be favorable for improving the (111) preferential orientation and decreasing the dispersion of the easy axis for magnetiza-tion. The measurement of time decay of magnetization gave rise to an activation volume as small as 6×10-25 m3, showing the promising perspective of being the recording medium for future high density perpendicular recording.
文摘FePt/Ag]10 multilayers were deposited on glass substrates by magnetron sputtering. After being annealed at 550℃ for 30 min, the coercivities of [FePt/Ag]10 multilayer films were observably improved. Magnetic properties of [FePt/Ag]10multilayer films are influenced by the Ag content. The highest coercivity is obtained for those multilayer films that the Ag content is about 25%. The analysis for the re- manence curves shows that the lower FePt layer thickness is favorable for decreasing the intergranular interaction. Re- sult of XRD shows that a thick Ag layer can enhance the intensity of FePt(001) peak. A magnetic activation volume of the order of 10?24 m3 is obtained by the measurement of magnetic viscosity, showing that it is promising to be ultra- high density recording media.
基金the National Natural Science Foundation of China (No. 60571010)the Open Foundation of the Key Laboratory of Ferroelectric and Piezoelectric Materials and Devices of Hubei Province in Hubei University
文摘FePt thin films and [FePt/Ag]n multilayer thin films were prepared by magnetron sputtering technique and subsequent annealing process. By comparing the microstructure and magnetic properties of these two kinds of thin films, effects of Ag addition on the structure and properties of FePt thin films were investigated. Proper Ag addition was found helpful for FePt phase transition at lower annealing temperature. With Ag addition, the magnetic domain pattern of FePt thin film changed from maze-like pattern to more discrete island-like domain pattern in [FePt/Ag]n multilayer thin films. In addition, introducing nonmagnetic Ag hindered FePt grains from growing larger. The in-depth defects in FePt films and [FePt/Ag]n multilayer films verify that Ag addition is attributed to a large number of pinning site defects in [FePt/Ag]n film and therefore has effects on its magnetic properties and microstructure.
基金supported by the National Natural Science Foundation of China(Grant Nos.11274033 and 61227902)the Research Fund for the Doctoral Programof Higher Education of China(Grant No.20131102130005)
文摘L10 FePt nanocomposite with high magnetocrystalline anisotropy energy has been extensively investigated in the fields of ultra-high density magnetic recording media. However, the order-disorder transition temperature of the nanocom- posite is higher than 600 ℃, which is a disadvantage for the use of the material due to the sustained growth of FePt grain under the temperature. To address the problem, addition of Ag atoms has been proposed, but the magnetic properties of the doped system are still unclear so far. Here in this paper, we use first-principles method to study the lattice parameters, formation energy, electronic structure, atomic magnetic moment and order-disorder transition temperature of L 10 FePt with Ag atom doping. The results show that the formation energy of a Ag atom substituting for a Pt site is 1.309 eV, which is lower than that of substituting for an Fe site 1.346 eV. The formation energy of substituting for the two nearest Pt sites is 2.560 eV lower than that of substituting for the further sites 2.621 eV, which indicates that Ag dopants tend to segregate L10 FePt. The special quasirandom structures （SQSs） for the pure FePt and the FePt doped with two Ag atoms at the stable Pt sites show that the order-disorder transition temperatures are 1377 ℃ and 600 ℃, respectively, suggesting that the transition temperature can be reduced with Ag atom, and therefore the FePt grain growth is suppressed. The satura- tion magnetizations of the pure FePt and the two Ag atoms doped FePt are 1083 emu/cc and 1062 emu/cc, respectively, indicating that the magnetic property of the doped system is almost unchanged.
基金supported by the Institute of Materials Chemistry, Shanxi Normal University, China
文摘[AIN/FePt]10, [AIN/FePt]10/Ag and Ag/[AIN/FePt]10 thin films were deposited by magnetron sputtering onto 7059 glass substrates, then were annealed at 550℃ for 30 min. It is found that introducing non-magnetic Ag underlayer can improve the ordering and （001） preferred orientation of FePt grains. Furthermore, the （001） texture of FePt grains increases with increasing Ag underlayer thickness. However, with Ag top layer given, it can only be observed that the ordering of FePt grains was promoted.
