Magnetic and Mössbauer-effect studies ofU6Fe hydride
摘要:
The dc magnetization, ac susceptibility, heat capacity, and Mossbauer effect for U6FeH17 and beta-UH3 have been examined as a function of temperature (4.2-300 K) and magnetic field up to 140 kOe. The U6FeH17 crystallizes in the Pm3n space group where the metal arrangement is like that of beta-W. The compound turned out to be a ferromagnet with a transition temperature of 173 K differing only slightly from that of beta-UH3. The saturation magnetization of U6FeH17 at 140 kOe and at 4.2 K is smaller than that for beta-UH3. The temperature dependence of the ac susceptibility showed a sharp maximum of the chi' and chi'' at the para-ferromagnetic transition temperature for both investigated hydrides. In the U6FeH17 hydride another steplike anomaly at about 140 K has been observed. This anomaly has been confirmed by heat capacity measurements. No such anomaly in beta-UH3 hydride has been reported for both mentioned above types of experiment. The valence-charge-density distribution and the main components of the electric field gradient tenser were calculated using the modified Thomas-Fermi approach. Mossbauer spectra analysis has shown that the iron atoms preferably occupy (6c) sites in the U6FeH17 lattice. It has been concluded that the [110] axis could be an easy magnetization direction in U6FeH17 hydride.
摘要 在 4.5-255 K 的温度范围内测量了 U 6 FeH 15 氢化物的热容 C p ( T )。观察到由磁相变引起的具有两个临界温度的复杂异常。低温最大值显示热滞后。较高的温度异常接近 β-UH 3 观察到的 T c 。跃迁的熵变化估计为5.43 J mol -1 K -1 。推导出电子比热系数γ ∗ = 33.8 mJ mol -1 K -2 。
Penetration depths of superconducting U6X (X = Fe, Co, Mn)
作者:M.K. Hou、C.Y. Huang、C.E. Olsen
DOI:10.1016/0038-1098(87)90936-7
日期:1987.1
Abstract The penetrationdepths, λ(T), of the heavy-fermion uranium-based superconductorsU6X (X = Fe, Co, Mn) have been measured as a function of temperature at ∼ 35 MHz. It was found that the temperature dependence of λ(T) for these compounds agrees well with the BCS theory. However, the values of λ(0) are large. By comparing the Slater-Pauling curve of the X elements with λ(0)-1 for the U6X superconductors
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作者:C. W. Kimball、P. P. Vaishnava、A. E. Dwight、James D. Jorgensen、F. Y. Fradin