共查询到20条相似文献,搜索用时 62 毫秒
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利用不同磁场下的R-T曲线,得到了Bi2Sr2-xLaxCuO6薄膜的上临界场Hc2,讨论了热激活磁通蠕动对上临界场Hc2的影响。用热激活磁通蠕动理论解释了磁场下R-T曲线的展宽效应,得到激活能对温度的线性变化关系,对磁场的指数变化关系。 相似文献
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在55-78K的温度范围内,最大磁场为2.3T下,用VSM测量了含Y2BaCuO5颗粒的区域熔炼YBa2Cu3O6+x的磁滞回线。利用Bean模型计算了磁临界电流密度,发现Jc与外加磁场H有一普适关系。实验结果能用集体钉扎理论解释。我们同时发现Y2BaCuO5(211)颗粒在磁通钉扎中有很大作用,在较高增场下,随211相颗粒含量的增加,样品的Jc下降越缓慢。 相似文献
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纳米银掺杂对Bi(2223)超导体的影响 总被引:1,自引:0,他引:1
研究了不同含量纳米银掺杂的(Bi,Pb)2Sr2Ca2Cu3Ox块材。DTA分析表明纳米银掺杂使材料熔点降低,加速了高Tc相的形成。磁场下R-T展宽测试表明,纳米银掺杂大大提高了磁通蠕动激活能,其中最佳掺杂15wt%Ag时激活能提高5~6倍;掺杂样品的钉扎能U(H)随磁场降低比非掺杂样品要慢,改善了磁场下的传输性能。交流磁化率测量表明纳米银掺杂使晶间损耗峰向高温移动20K,说明纳米银掺杂改善了晶界 相似文献
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我们用 Hall 效应和磁场下展宽的电阻-温度(R-T)曲线研究了 YBa_2Cu_3O_(7-δ)外延生长薄膜中的磁通运动规律.从展宽的 R-T 曲线中,得到了磁通蠕动激活能与磁场之间满足的指数关系;而从 Hall 系数 R_H 的测量中,发现了与 R-T 展宽相对应的 Hall 系数反常变化.对整个 R-T 和 R_H-T 曲线的变化,我们借用磁通玻璃模型来进行描述,从不同的角度,揭示了磁通运动的规律. 相似文献
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测量了Si(100)(2×1)-H表面和Si(100)(3×1)-H表面的反射二次谐波强度随温度的变化关系,并与清洁的Si(100)(2×1)表面进行了比较。Si(100)(2×1)表面和Si(100)(3×1)-H表面的二次谐波强度随温度的上升而单调地减小,Si(100)(2×1)-H表面二次谐波强度随温度的变化不是单调的,约在470K时信号最大。可以根据二次谐波信号的强度及其随温度的变化关系来确定样品温度和表面结构。 相似文献
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Neutron diffraction study of polycrystalline HoRu2Si2, HoRh2Si2, TbRh2Si2, and TbIr2Si2 was performed in the temperature range between 4.2 and 300 K. For HoRu2Si2 the magnetic spin alignment of a linear transverse wave mode below the Néel temperature 19 K is observed. This static moment wave is propagating along the b-axis with k=(0, 0.2, 0) and is polarized in the c-axis. The root-mean-square and maximum saturation moments per Ho atom are 9.26 and 13.09μB, respectively. HoRh2Si2, TbRh2Si2 an TbIr2Si2 are simple collinear antiferromagnets of +-+- type with Néel temperatures of (27±1), (98±2) and (72±3) K, respectively. For TbRh2Si2 and TbIr2Si2 magnetic moments are localized on RE ions only and are aligned along the tetragonal axis, while for HoRh2Si2 they form an angle ø = (28±3)°. 相似文献
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P. Dalmas de Réotier B. Licciardi A. Yaouanc B. Chevalier P. Chaudouët R. Madar J. P. Sanchez 《Hyperfine Interactions》1990,59(1-4):317-320
Muon spin relaxation experiments have been carried out in the paramagnetic and magnetically ordered states of URh2Si2 and CeRh2Si2. As the magnetic structure of these compounds is well known, these measurements can help to characterise their magnetic properties
probed by μSR and to understand the μSR results of the heavy fermion compounds of the same crystallographic family. Our measurements
show that the muons occupy two different crystallographic sites. The spectra of URh2Si2 and CeRh2Si2 in the magnetically ordered states are very different, probably reflecting their different magnetic structures. The spectra
obtained on CeRh2Si2 are similar to the published spectra of the heavy fermion compound CeCu2.1 Si2. Muon spin rotation measurements on LaNi2As2 indicate that the muon is diffusing at 150 K. 相似文献
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The CO2 TEA laser irradiation of CBr2F2 in the presence of Cl2 yielded 13C-enriched CBrClF2 and 13C-enriched CCl2F2 under selected experimental conditions. As the photolysis proceeded, the 13C concentration of CBrClF2 decreased gradually and that of CCl2F2 increased up to 90% or higher. These results can be explained by the mechanism involving the secondary 13C-selective IRMPD of the primary product CBrClF2. On the other hand, the carbon-containing product for a CCl2F2/Br2 system was only CBrClF2; the further IRMPD of which probably regenerated CBrClF2 in the presence of Br2. The decomposition probabilities of 12C- and 13C-containing molecules in both systems were measured as functions of laser line, laser fluence, and reactant pressures. 相似文献
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Guo Guanghua R. Z. Levitin V. V. Snegirev D. V. Filippov 《Physics of the Solid State》2001,43(3):496-500
Longitudinal and transverse magnetostrictions of polycrystalline samples of intermetallic compounds RMn2Ge2 (R=Sm or Gd) are measured in pulsed magnetic fields up to 250 kOe. It is found that linear magnetostrictive strains of about 10?3 arise in a temperature range in which the magnetic field causes a change in the magnetic state of a manganese magnetic subsystem. The results obtained are described within the model of a two-sublattice ferrimagnet with a negative exchange interaction in the manganese subsystem in terms of a strong dependence of this interaction on interatomic distances. 相似文献
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J. Petzelt I. Mayerová Č. Bárta L. D. Kislovskii 《Czechoslovak Journal of Physics》1973,23(8):845-854
Far infrared (30–430 cm?1) reflectivity measurements of Hg2Cl2 and Hg2Br2 single crystals have been performed in polarized light. The spectra, which are in agreement with group-theoretical predictions, were analyzed by the oscillator fitting procedure and Kramers-Kronig method. The results are compared with the existing data from other measurements and the large anisotropy of polar modes is briefly discussed. The polarization vectors of all long-wavelength symmetry modes were determined group-theoretically. 相似文献
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《中国科学:物理学 力学 天文学(英文版)》2018,(12)
正Since the discovery of superconductivity in LaFeAsO_(1-x)F_x,the high-T_c iron-based superconductors have been extensively studied from both experimental and theoretical viewpoints [1-8]. However, the mechanism of the unconventional superconductivity is still to be resolved. To 相似文献
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H. Oesterreicher 《Journal of Physics and Chemistry of Solids》1973,34(7):1267-1280
Both pseudobinary systems exhibit large homogeneous regions of cubic and hexagonal Laves phases. Ordering tendencies on crystallographic sites between Al and the transition metals are observed in the hexagonal type.Electron transfer to the transition metals quenches their moments so that they become nonmagnetic at high Al concentrations. The peculiarities in the mechanism of magnetization which appear in rare earth dialuminides when Al is replaced by a transition metal have been studied in detail at cryogenic temperatures.The first replacement of Al results in a decrease in saturation moment. Neutron diffraction verifies the low ordered rare earth sublattice moments and reveals the ‘lost part’ as a disordered component. Considerable magnetic hardness develops in certain regions of concentration often connected with spontaneous increases in magnetization with field. All available evidence suggests the presence of unusual domain wall effects to be responsible for this effect. High remanences develop in both the hexagonal and in the cubic structures in the intermediate region. The development of disordered magnetic components is connected either with the disorder on crystallographic sites or changes in the free electron concentration. 相似文献