The present study reports the magnetizations and magneto-transport properties of PrFel_xNixO3 thin films grown by pulsed laser ablation technique on LaA103 snbstrates. From DC M/H plots of these films, weak ferromagne...The present study reports the magnetizations and magneto-transport properties of PrFel_xNixO3 thin films grown by pulsed laser ablation technique on LaA103 snbstrates. From DC M/H plots of these films, weak ferromagnetism or ferrimagnetism behaviors are observed. With Ni substitution, reduction in saturation magnetization is also seen. With Ni doping, variations in saturation field （Hs）, coercive field （Hc）, Weiss temperature （0）, and effective magnetic moment （Pelf） are seen. A small change of magnetoresitance with application of higher field is observed. Various essential parameters like density of state （Nf） at Fermi level, Mott＇s characteristic temperature （To）, and activation energy （Ea） in the presence of and in the absence of magnetic field are calculated. The present observed magnetic properties are related to the change of Fe-O bond length （causing an overlap between the oxygen p orbital and iron d orbital） and the deviation of the Fe-O-Fe angle from 180~. Reduction of magnetic domain after Ni doping is also explored to explain the present observed magnetic behavior of the system. The influence of doping on various transport properties in these thin films indicates a distortion in the lattice structure and single particle band width, owing to stress-induced reduction in unit cell volume.展开更多
The specific heats of both a two-layer ferromagnetic superlattice and a two-layer ferrimagnetic one arestudied.It is found that the spin quantum numbers,the interlayer and intralayer exchange couplings,the anisotropy,...The specific heats of both a two-layer ferromagnetic superlattice and a two-layer ferrimagnetic one arestudied.It is found that the spin quantum numbers,the interlayer and intralayer exchange couplings,the anisotropy,theapplied magnetic field,and the temperature all affect the specific heat of these superlattices.For both the ferromagneticand ferrimagnetic superlattices,the specific heat decreases with increasing the spin quantum number,the absolutevalue of interlayer exchange coupling,intralayer exchange coupling,and anisotropy,while it increases with increasingtemperature at low temperatures.When an applied magnetic field is enhanced,the specific heat decreases in the two-layerferromagnetic superlattice,while it is almost unchanged in the two-layer ferrimagnetic superlattice at low fieldrange at low temperatures.展开更多
Gear-shape CeO2 microstructures have been synthesized via a facile hydrothermal method with Ce（NO3）3-6H20 as the cerium source, NHaHCO3 as both the precipitator and the carbon source, and cetyltrimethyl ammonium bro...Gear-shape CeO2 microstructures have been synthesized via a facile hydrothermal method with Ce（NO3）3-6H20 as the cerium source, NHaHCO3 as both the precipitator and the carbon source, and cetyltrimethyl ammonium bromide （CTAB） as the surfactant. X-ray diffraction （XRD） inferred that the synthesized CeO2 microstructures exhibited a fluorite structure. The band gap （Eg） of CeO2 samples is larger than that of bulk. X-ray photoelectron spectroscopy （XPS） showed that there are plenty or Ce3＋ ions and oxygen vacancies at the surface of CeO2 samples. All the synthesized CeO2 samples exhibited the room temperature ferromagnetism, and the saturation magnetization increases with the increases of lattice parameter and Eg. The room temperature ferromagnetism mechanism of gear-shape CeO2 is mainly attributed to the influence Ce3＋ ions.展开更多
In this paper, a novel approach is presented to synthesize microwave medium of negative refractive index by incorporating metallic wire array with negative effective permittivity into the host media such as ferrimagne...In this paper, a novel approach is presented to synthesize microwave medium of negative refractive index by incorporating metallic wire array with negative effective permittivity into the host media such as ferrimagnet-YIG (yttrium iron garnet) applied by external magnetic field whose permeability is negative. We have designed the composite medium having negative refractive index in C/X band frequencies, analyzed and simulated its electromagnetic (EM) properties by use of EM EDA package based on time-domain finite integration method. The simulation results show that: ① the effective permittivity of the designed metallic wire array is negative in the frequency range from 7.02 GHz to 9.80 GHz; ② the permeability of YIG substrate immersed into an external magnetic field is negative in the frequency range from 5.22 GHz to 8.14 GHz; ③ EM wave can pass through the composite medium synthesized by the above designed metallic wire array and YIG substrate, and ④ the negative refraction behavior occurs on the interface between the composite medium and the normal material with positive refractive index in 7.51―8.13 GHz frequency range, in which the effective permittivity of the metallic wire array and the permeability of YIG substrate are negative simultaneously. The full wave simulation has demonstrated that the effective refractive index of the designed composite medium is indeed negative and ascertained that the proposed approach to design microwave medium with negative refractive index is viable.展开更多
基金supported by the Natural Science Foundation of Liaoning Province under Grant No.20041021the Scientific Foundation of the Educational Department of Liaoning Province under Grant Nos.2004C006 and 20060638the Postdoctoral Foundation of Shenyang University of Technology
文摘The present study reports the magnetizations and magneto-transport properties of PrFel_xNixO3 thin films grown by pulsed laser ablation technique on LaA103 snbstrates. From DC M/H plots of these films, weak ferromagnetism or ferrimagnetism behaviors are observed. With Ni substitution, reduction in saturation magnetization is also seen. With Ni doping, variations in saturation field （Hs）, coercive field （Hc）, Weiss temperature （0）, and effective magnetic moment （Pelf） are seen. A small change of magnetoresitance with application of higher field is observed. Various essential parameters like density of state （Nf） at Fermi level, Mott＇s characteristic temperature （To）, and activation energy （Ea） in the presence of and in the absence of magnetic field are calculated. The present observed magnetic properties are related to the change of Fe-O bond length （causing an overlap between the oxygen p orbital and iron d orbital） and the deviation of the Fe-O-Fe angle from 180~. Reduction of magnetic domain after Ni doping is also explored to explain the present observed magnetic behavior of the system. The influence of doping on various transport properties in these thin films indicates a distortion in the lattice structure and single particle band width, owing to stress-induced reduction in unit cell volume.
基金Supported by the Natural Science Foundation of Liaoning Province of China under Grant No.20062040
文摘The specific heats of both a two-layer ferromagnetic superlattice and a two-layer ferrimagnetic one arestudied.It is found that the spin quantum numbers,the interlayer and intralayer exchange couplings,the anisotropy,theapplied magnetic field,and the temperature all affect the specific heat of these superlattices.For both the ferromagneticand ferrimagnetic superlattices,the specific heat decreases with increasing the spin quantum number,the absolutevalue of interlayer exchange coupling,intralayer exchange coupling,and anisotropy,while it increases with increasingtemperature at low temperatures.When an applied magnetic field is enhanced,the specific heat decreases in the two-layerferromagnetic superlattice,while it is almost unchanged in the two-layer ferrimagnetic superlattice at low fieldrange at low temperatures.
基金financially supported by the National Natural Science Foundation of China(No.50502005)Beijing Natural Science Foundation(No.1092014)+2 种基金Open Project of Key Laboratory for Magnetism and Magnetic Materials of the Ministry of Education,Lanzhou University(LZUMMM2010002)Metallurgy Foundation of University of Science and Technology Beijingsupported by Program for New Century Excellent Talents in University(No.NCET-070065)
基金financially supported by the Anhui Provincial Natural Science Foundation (No. 1508085SME219)
文摘Gear-shape CeO2 microstructures have been synthesized via a facile hydrothermal method with Ce（NO3）3-6H20 as the cerium source, NHaHCO3 as both the precipitator and the carbon source, and cetyltrimethyl ammonium bromide （CTAB） as the surfactant. X-ray diffraction （XRD） inferred that the synthesized CeO2 microstructures exhibited a fluorite structure. The band gap （Eg） of CeO2 samples is larger than that of bulk. X-ray photoelectron spectroscopy （XPS） showed that there are plenty or Ce3＋ ions and oxygen vacancies at the surface of CeO2 samples. All the synthesized CeO2 samples exhibited the room temperature ferromagnetism, and the saturation magnetization increases with the increases of lattice parameter and Eg. The room temperature ferromagnetism mechanism of gear-shape CeO2 is mainly attributed to the influence Ce3＋ ions.
基金Supported by the National Natural Science Foundation of China (Grant No. 60571024) Key Science and Technology Foundation for Youth of UESTC (Grant No. JX04001)
文摘In this paper, a novel approach is presented to synthesize microwave medium of negative refractive index by incorporating metallic wire array with negative effective permittivity into the host media such as ferrimagnet-YIG (yttrium iron garnet) applied by external magnetic field whose permeability is negative. We have designed the composite medium having negative refractive index in C/X band frequencies, analyzed and simulated its electromagnetic (EM) properties by use of EM EDA package based on time-domain finite integration method. The simulation results show that: ① the effective permittivity of the designed metallic wire array is negative in the frequency range from 7.02 GHz to 9.80 GHz; ② the permeability of YIG substrate immersed into an external magnetic field is negative in the frequency range from 5.22 GHz to 8.14 GHz; ③ EM wave can pass through the composite medium synthesized by the above designed metallic wire array and YIG substrate, and ④ the negative refraction behavior occurs on the interface between the composite medium and the normal material with positive refractive index in 7.51―8.13 GHz frequency range, in which the effective permittivity of the metallic wire array and the permeability of YIG substrate are negative simultaneously. The full wave simulation has demonstrated that the effective refractive index of the designed composite medium is indeed negative and ascertained that the proposed approach to design microwave medium with negative refractive index is viable.
