granular magnetic Co_(x)Cu_(1-x)(x=0.05-0.5)alloy ribbons were prepared by melt spinning method,and the structural,magnetotransport,magnetic properties and the effects of annealing on these properties were studied by ...granular magnetic Co_(x)Cu_(1-x)(x=0.05-0.5)alloy ribbons were prepared by melt spinning method,and the structural,magnetotransport,magnetic properties and the effects of annealing on these properties were studied by x-ray diffraction,vibrating sample magnetometer,magnetoresistance measurement at room temperature.Giant magnetoresistance was observed over a broad range of Co concentrations with a maximum magnetoresistance(MR)ratio of 7.8%(at x=0.20 and 500℃ annealing)under a magnetic field of 20kOe.The MR ratio increases with the annealing temperature and reaches a maximum at about 500℃ and then drops.The dependence of MR and magnetization on magnetic field for various granule parameters were studied by controlling the nucleation and growth of Co granules.展开更多
Ma.gnetiza.tion,Curie teiiiperti.ture mid crystallization temperature measurements for amorphous(Fe_(1-x)Nd_(x))_(100-y)B_(y) iilloys with y=6,18.5 and 25 have been made.Spon-taneous magnetization shows a monotonic de...Ma.gnetiza.tion,Curie teiiiperti.ture mid crystallization temperature measurements for amorphous(Fe_(1-x)Nd_(x))_(100-y)B_(y) iilloys with y=6,18.5 and 25 have been made.Spon-taneous magnetization shows a monotonic decrease with x,and the noncollinear spin structures have been proposed to expluin the observed results.The composition dependence of Curie tenipertitiire is exphtined by the average niolecular-field model.The substitu lion of siim.ll N<1 for Fc is found to have a strong enha.nccinent of the theriiml stability in amorphous Fe-Nd-B alloys.展开更多
The magnetization curves at 1.5K and Curie temperature of amorphow (Fe_(100-x)B_(x))_(88)Nd_(12±ε) alloys were measured.Their spontaneous magnetizations is explained by a noncollinear structure.The average magne...The magnetization curves at 1.5K and Curie temperature of amorphow (Fe_(100-x)B_(x))_(88)Nd_(12±ε) alloys were measured.Their spontaneous magnetizations is explained by a noncollinear structure.The average magnetic moment μ_(Fe) per Fe atom decreases monotonically with increasing x,and becomes more rapid when x>24.The B content dependence of Curie temperature shows a mazimum at x=15.At x<15,the increase of T_(c) with x may be attributed to the indirect exchange interactions between Fe-Fe atoms.展开更多
Magnetic properties and crystallization of amorphous Fe_(62)Co_(15.5)Nd_(4)B_(18.5) alloy are studied.The Curie temperature of the present sample is 127K higher than that of amorphous Fe_(77.5)Nd_(4)B_(18.5) alloy,but...Magnetic properties and crystallization of amorphous Fe_(62)Co_(15.5)Nd_(4)B_(18.5) alloy are studied.The Curie temperature of the present sample is 127K higher than that of amorphous Fe_(77.5)Nd_(4)B_(18.5) alloy,but their crystallization temperature is compatible with each other.A coercive field of 2.34kOe,a remanence of 12.3kG and an energy product of 11.6MGOe are obtained at room temperature in the Fe_(62)Co_(15.5)Nd_(4)B_(18.5) alloy annealed at 650°C.The 15.5at.%-Co substitution for Fe results in an increase of about 1l0K in Tc of 2:14:1 phase.展开更多
The magnetization curves at 1.5K and thermomagnetization curves in the fields of about 450e for amorphous Fe_(90-x)Si_(x)Zr_(10)(x=0,4,7 and 10)alloys prepared by the drum spinning technique are measured with an eztra...The magnetization curves at 1.5K and thermomagnetization curves in the fields of about 450e for amorphous Fe_(90-x)Si_(x)Zr_(10)(x=0,4,7 and 10)alloys prepared by the drum spinning technique are measured with an eztracting sample magnetometer.At low Si concentration the amorphous Fe_(90-x)Si_(x)Zr_(10) alloys exhibit a large value of the high-field susceptibility,but the average magnetic moment per Fe atomμFe,and the Curie temperature,Tc,are quite small,compared with amorphous Fe_(87-x)Si_(x)B_(13) alloys.This unusual behavior could be explained in terms of the presence of the antiferromagnetic state.展开更多
The influence of substituting V for Fe on the magnetic properties of amorphous Fe_(90-x)V_(x)Zr_(10) alloys have been systematically investigated.A clear max-ium in Curie temperature,a decrease of high-field susceptib...The influence of substituting V for Fe on the magnetic properties of amorphous Fe_(90-x)V_(x)Zr_(10) alloys have been systematically investigated.A clear max-ium in Curie temperature,a decrease of high-field susceptibility and magnetic moment with addition of V was observed.展开更多
In the reduced curves of electronic resistivity and thermomagnetic measurement of the amorphous alloys,(Fe_(1-x)Ni_(x))_(84)B_(16) with 0.02<x<0.08,preheated to a temperature higher than that of crystallization,...In the reduced curves of electronic resistivity and thermomagnetic measurement of the amorphous alloys,(Fe_(1-x)Ni_(x))_(84)B_(16) with 0.02<x<0.08,preheated to a temperature higher than that of crystallization,an anomalous abruption at about 150℃ was observed.The results of differential thermal analysis(DTA)and of X-ray diffraction show that after crystallization of the amorphous alloys(Fe_(1-x)Ni_(x))_(84)B_(16) the anomalous abruption can be attributed to the martensitic transformation of γ Fe(Ni)to α Fe(Ni).展开更多
Multiphase Fe-oxide thin films are fabricated on glass substrates by a facing-target sputtering tech- nique. X-ray diffraction and X-ray photoelectron spectroscopy reveal that Fe, Fe3BO4, γ -Fe2BO3B and FeO coexist i...Multiphase Fe-oxide thin films are fabricated on glass substrates by a facing-target sputtering tech- nique. X-ray diffraction and X-ray photoelectron spectroscopy reveal that Fe, Fe3BO4, γ -Fe2BO3B and FeO coexist in the films. High resolution transmission electron microscopy shows the well-defined colum- nar grain structure with the unoxidized Fe as the core and iron-oxide as the shell. The low-field positive and high-field negative magnetoresistances coexist in such a system at room temperature, which can be explained by considering a shell/core model. Nonlinear current-voltage curve and photovoltaic effect further confirm the tunneling-type conduction.展开更多
基金Supported by the National Natural Science Foundation of Chinaby the State Key Laboratory of Magnet ism,Institute of Physics,Chmese Academy of Sciences.
文摘granular magnetic Co_(x)Cu_(1-x)(x=0.05-0.5)alloy ribbons were prepared by melt spinning method,and the structural,magnetotransport,magnetic properties and the effects of annealing on these properties were studied by x-ray diffraction,vibrating sample magnetometer,magnetoresistance measurement at room temperature.Giant magnetoresistance was observed over a broad range of Co concentrations with a maximum magnetoresistance(MR)ratio of 7.8%(at x=0.20 and 500℃ annealing)under a magnetic field of 20kOe.The MR ratio increases with the annealing temperature and reaches a maximum at about 500℃ and then drops.The dependence of MR and magnetization on magnetic field for various granule parameters were studied by controlling the nucleation and growth of Co granules.
文摘Ma.gnetiza.tion,Curie teiiiperti.ture mid crystallization temperature measurements for amorphous(Fe_(1-x)Nd_(x))_(100-y)B_(y) iilloys with y=6,18.5 and 25 have been made.Spon-taneous magnetization shows a monotonic decrease with x,and the noncollinear spin structures have been proposed to expluin the observed results.The composition dependence of Curie tenipertitiire is exphtined by the average niolecular-field model.The substitu lion of siim.ll N<1 for Fc is found to have a strong enha.nccinent of the theriiml stability in amorphous Fe-Nd-B alloys.
文摘The magnetization curves at 1.5K and Curie temperature of amorphow (Fe_(100-x)B_(x))_(88)Nd_(12±ε) alloys were measured.Their spontaneous magnetizations is explained by a noncollinear structure.The average magnetic moment μ_(Fe) per Fe atom decreases monotonically with increasing x,and becomes more rapid when x>24.The B content dependence of Curie temperature shows a mazimum at x=15.At x<15,the increase of T_(c) with x may be attributed to the indirect exchange interactions between Fe-Fe atoms.
文摘Magnetic properties and crystallization of amorphous Fe_(62)Co_(15.5)Nd_(4)B_(18.5) alloy are studied.The Curie temperature of the present sample is 127K higher than that of amorphous Fe_(77.5)Nd_(4)B_(18.5) alloy,but their crystallization temperature is compatible with each other.A coercive field of 2.34kOe,a remanence of 12.3kG and an energy product of 11.6MGOe are obtained at room temperature in the Fe_(62)Co_(15.5)Nd_(4)B_(18.5) alloy annealed at 650°C.The 15.5at.%-Co substitution for Fe results in an increase of about 1l0K in Tc of 2:14:1 phase.
文摘The magnetization curves at 1.5K and thermomagnetization curves in the fields of about 450e for amorphous Fe_(90-x)Si_(x)Zr_(10)(x=0,4,7 and 10)alloys prepared by the drum spinning technique are measured with an eztracting sample magnetometer.At low Si concentration the amorphous Fe_(90-x)Si_(x)Zr_(10) alloys exhibit a large value of the high-field susceptibility,but the average magnetic moment per Fe atomμFe,and the Curie temperature,Tc,are quite small,compared with amorphous Fe_(87-x)Si_(x)B_(13) alloys.This unusual behavior could be explained in terms of the presence of the antiferromagnetic state.
文摘The influence of substituting V for Fe on the magnetic properties of amorphous Fe_(90-x)V_(x)Zr_(10) alloys have been systematically investigated.A clear max-ium in Curie temperature,a decrease of high-field susceptibility and magnetic moment with addition of V was observed.
文摘In the reduced curves of electronic resistivity and thermomagnetic measurement of the amorphous alloys,(Fe_(1-x)Ni_(x))_(84)B_(16) with 0.02<x<0.08,preheated to a temperature higher than that of crystallization,an anomalous abruption at about 150℃ was observed.The results of differential thermal analysis(DTA)and of X-ray diffraction show that after crystallization of the amorphous alloys(Fe_(1-x)Ni_(x))_(84)B_(16) the anomalous abruption can be attributed to the martensitic transformation of γ Fe(Ni)to α Fe(Ni).
基金Supported by the National Natural Science Foundation of China (Grant Nos. 50672132 and 60576015) the Key Project of Chinese Ministry of Education (Grant No. 107020)
文摘Multiphase Fe-oxide thin films are fabricated on glass substrates by a facing-target sputtering tech- nique. X-ray diffraction and X-ray photoelectron spectroscopy reveal that Fe, Fe3BO4, γ -Fe2BO3B and FeO coexist in the films. High resolution transmission electron microscopy shows the well-defined colum- nar grain structure with the unoxidized Fe as the core and iron-oxide as the shell. The low-field positive and high-field negative magnetoresistances coexist in such a system at room temperature, which can be explained by considering a shell/core model. Nonlinear current-voltage curve and photovoltaic effect further confirm the tunneling-type conduction.
