FePt films with a high degree of order S of the L10 structure （S 〉 0.90） and well defined [001] crystalline growth perpendicular to the film plane are fabricated on thermally oxidized Si substrates by the addition ...FePt films with a high degree of order S of the L10 structure （S 〉 0.90） and well defined [001] crystalline growth perpendicular to the film plane are fabricated on thermally oxidized Si substrates by the addition of ZnO and a successive rapid thermal annealing （RTA） process. The optimum condition to prepare high-ordering L10 FePtZnO films is 20 vol% ZnO addition and 450 ℃ annealing. The effect of the ZnO additive on the ordering process of the L10 FePtZnO films is discussed. In the annealing process, Zn atoms move to the film surface and evaporate. The motion of the Zn atoms accelerates the intergrain exchange and decreases the ordering temperature.展开更多
The films of Ti(15 nm)/Ni(t nm)/Ti(15 nm)(t=20, 30, 40, 50) were prepared by dc magnetron sputtering at room temperature and subsequent annealing at 400 ℃ for 30 min. Scanning probe microscope (SPM), vibrating sample...The films of Ti(15 nm)/Ni(t nm)/Ti(15 nm)(t=20, 30, 40, 50) were prepared by dc magnetron sputtering at room temperature and subsequent annealing at 400 ℃ for 30 min. Scanning probe microscope (SPM), vibrating sample magnetometer (VSM) and X-ray diffraction (XRD) were applied to study the magnetic properties and microstructure. AFM images show that small and uniform grains and some clusters appear with the increase of Ni thickness, also MFM images show that the size of domain first decreases and then increases. The coercivity reaches the maximum 48 kA·m-1 at t=30 nm. The XRD profiles show stronger fcc (111) orientation peak of Ni and weak hcp structure peaks of Ni3Ti. This results reveal that the crystal lines have the prefer orientation and achieve the ordered.展开更多
An Si(001)/SiO2/Ti/Pt/Fe/Cu multilayer was prepared by direct-current magnetic sputtering system. The phase composition of the film was characterized by X-ray diffractometry(XRD), and the microstructure was observed b...An Si(001)/SiO2/Ti/Pt/Fe/Cu multilayer was prepared by direct-current magnetic sputtering system. The phase composition of the film was characterized by X-ray diffractometry(XRD), and the microstructure was observed by scanning electronic microscopy(SEM). Through the film annealed in magnetic field perpendicular to the surface of the film, FCC FePt film with (001) texture was obtained. And the density of the particle in the film annealed without magnetic field is very small compared with that in the film annealed with magnetic field. And the effect of magnetic field annealing on the microstructure of Fe/Pt film and the segregation of FCC FePt phase were also discussed.展开更多
The study on temperature dependence of exchange bias field and coercivity is crucial to solving the writing/reading dilemma in magnetic recording.Motivated by recent experimental findings,a complete switch between exc...The study on temperature dependence of exchange bias field and coercivity is crucial to solving the writing/reading dilemma in magnetic recording.Motivated by recent experimental findings,a complete switch between exchange bias field and coercivity with temperature is proposed,and the performance,characterized by average switching temperature(T_(S))and switching temperature width(T_(W)),controlled by antiferromagnetic anisotropy(KAF)and exchange coupling(J_(AF))constants is studied based on a MonteCarlo simulation.The results show that a linear relationship between T_(S)and KAFis established when KAFis above a critical value,while T_(S)is weakly influenced by J_(AF).On the contrary,T_(W)is insensitive to KAF,while strongly depends on J_(AF).Besides overcoming thermal energy,the increase of KAFfor a small J_(AF)guarantees the completely frozen states in the antiferromagnetic layers during magnetizing at higher temperature,below which the exchange bias field exists with a negligible coercivity.Otherwise,for a large J_(AF),the uncompensated antiferromagnetic magnetization behavior during the ferromagnetic magnetization reversal becomes complicated,and the switching process in the low temperature range depends on the irreversibility of uncompensated antiferromagnetic magnetization reversal during magnetizing,while in the high temperature range mainly influenced by the field-cooling process,resulting in a large T_(W).This work provides an opportunity to control/optimize the performance of the temperatureinduced switch between unidirectional and uniaxial symmetries through precisely tuning KAFand/or J_(AF)to meet different application demands in the next generation information technology.展开更多
采用双主相工艺制备了名义成分为Di_(26.8)Ce_(5.6)Fe_(bal)Al_(0.3)Cu_(0.2)Co_(1.0)B_(1.0)的烧结磁体,烧结后分别在440℃、470℃、500℃、530℃进行不同温度回火处理。结果表明,磁体剩磁在回火前后基本没有变化,但是磁体矫顽力却对...采用双主相工艺制备了名义成分为Di_(26.8)Ce_(5.6)Fe_(bal)Al_(0.3)Cu_(0.2)Co_(1.0)B_(1.0)的烧结磁体,烧结后分别在440℃、470℃、500℃、530℃进行不同温度回火处理。结果表明,磁体剩磁在回火前后基本没有变化,但是磁体矫顽力却对回火温度较为敏感:在440℃回火时矫顽力最高,达到1091 k A/m;在530℃回火时矫顽力最低,为936 k A/m。对比各样品回火前后的背散射像发现,440℃回火后微观结构并没有明显变化,当温度提高至470℃以上时晶界相变得连续且团块晶界相占比变大。EDS点分析和XRD结果显示,随着回火温度提高,晶界相中Ce含量逐步增高,且富Ce相及CeFe_(2)相衍射峰区域明显,而Nd_(2)Fe_(14)B主相占比逐步减少。富Ce合金的DSC分析结果发现,在424℃左右出现吸热峰,很可能是富Ce与CeFe_(2)相产生的相变点。晶界中Ce含量的提高可能降低各主相晶粒外延区的各向异性场,从而降低磁体矫顽力。展开更多
文摘FePt films with a high degree of order S of the L10 structure （S 〉 0.90） and well defined [001] crystalline growth perpendicular to the film plane are fabricated on thermally oxidized Si substrates by the addition of ZnO and a successive rapid thermal annealing （RTA） process. The optimum condition to prepare high-ordering L10 FePtZnO films is 20 vol% ZnO addition and 450 ℃ annealing. The effect of the ZnO additive on the ordering process of the L10 FePtZnO films is discussed. In the annealing process, Zn atoms move to the film surface and evaporate. The motion of the Zn atoms accelerates the intergrain exchange and decreases the ordering temperature.
基金The work was financially supported by the National Natural Science Foundation of China (No.10274018), the Foundation of Hebei Provincial Education Department (No.2002116), and the Key foundation of Hebei Normal University (No. Z200102).
文摘The films of Ti(15 nm)/Ni(t nm)/Ti(15 nm)(t=20, 30, 40, 50) were prepared by dc magnetron sputtering at room temperature and subsequent annealing at 400 ℃ for 30 min. Scanning probe microscope (SPM), vibrating sample magnetometer (VSM) and X-ray diffraction (XRD) were applied to study the magnetic properties and microstructure. AFM images show that small and uniform grains and some clusters appear with the increase of Ni thickness, also MFM images show that the size of domain first decreases and then increases. The coercivity reaches the maximum 48 kA·m-1 at t=30 nm. The XRD profiles show stronger fcc (111) orientation peak of Ni and weak hcp structure peaks of Ni3Ti. This results reveal that the crystal lines have the prefer orientation and achieve the ordered.
文摘An Si(001)/SiO2/Ti/Pt/Fe/Cu multilayer was prepared by direct-current magnetic sputtering system. The phase composition of the film was characterized by X-ray diffractometry(XRD), and the microstructure was observed by scanning electronic microscopy(SEM). Through the film annealed in magnetic field perpendicular to the surface of the film, FCC FePt film with (001) texture was obtained. And the density of the particle in the film annealed without magnetic field is very small compared with that in the film annealed with magnetic field. And the effect of magnetic field annealing on the microstructure of Fe/Pt film and the segregation of FCC FePt phase were also discussed.
基金financially supported by the National Natural Science Foundation of China(No.11774045)the Joint Research Fund Liaoning-Shenyang National Laboratory for Materials Science(No.20180510008)。
文摘The study on temperature dependence of exchange bias field and coercivity is crucial to solving the writing/reading dilemma in magnetic recording.Motivated by recent experimental findings,a complete switch between exchange bias field and coercivity with temperature is proposed,and the performance,characterized by average switching temperature(T_(S))and switching temperature width(T_(W)),controlled by antiferromagnetic anisotropy(KAF)and exchange coupling(J_(AF))constants is studied based on a MonteCarlo simulation.The results show that a linear relationship between T_(S)and KAFis established when KAFis above a critical value,while T_(S)is weakly influenced by J_(AF).On the contrary,T_(W)is insensitive to KAF,while strongly depends on J_(AF).Besides overcoming thermal energy,the increase of KAFfor a small J_(AF)guarantees the completely frozen states in the antiferromagnetic layers during magnetizing at higher temperature,below which the exchange bias field exists with a negligible coercivity.Otherwise,for a large J_(AF),the uncompensated antiferromagnetic magnetization behavior during the ferromagnetic magnetization reversal becomes complicated,and the switching process in the low temperature range depends on the irreversibility of uncompensated antiferromagnetic magnetization reversal during magnetizing,while in the high temperature range mainly influenced by the field-cooling process,resulting in a large T_(W).This work provides an opportunity to control/optimize the performance of the temperatureinduced switch between unidirectional and uniaxial symmetries through precisely tuning KAFand/or J_(AF)to meet different application demands in the next generation information technology.
文摘采用双主相工艺制备了名义成分为Di_(26.8)Ce_(5.6)Fe_(bal)Al_(0.3)Cu_(0.2)Co_(1.0)B_(1.0)的烧结磁体,烧结后分别在440℃、470℃、500℃、530℃进行不同温度回火处理。结果表明,磁体剩磁在回火前后基本没有变化,但是磁体矫顽力却对回火温度较为敏感:在440℃回火时矫顽力最高,达到1091 k A/m;在530℃回火时矫顽力最低,为936 k A/m。对比各样品回火前后的背散射像发现,440℃回火后微观结构并没有明显变化,当温度提高至470℃以上时晶界相变得连续且团块晶界相占比变大。EDS点分析和XRD结果显示,随着回火温度提高,晶界相中Ce含量逐步增高,且富Ce相及CeFe_(2)相衍射峰区域明显,而Nd_(2)Fe_(14)B主相占比逐步减少。富Ce合金的DSC分析结果发现,在424℃左右出现吸热峰,很可能是富Ce与CeFe_(2)相产生的相变点。晶界中Ce含量的提高可能降低各主相晶粒外延区的各向异性场,从而降低磁体矫顽力。
