De Haas-van Alphen effect in uranium and ytterbium Compounds

在稀土离子最近邻距离d_小于某个临界值（近似等于0.45nm）的镱和铀化合物中观察到价态涨落和重费米子现象<R-R>。d_的减小<R-R>预期将增加稀土离子的传导电子与4-f电子之间的杂化。本文测量了YbZn_<11>（d_<R-R>=0.569nm），YbSn_3（d_<R-R>=0.468nm），YbBi_2（d_<R-R>=0.420nm），YbAl_3（d_ = <R-R>0.420nm）和UGa_2（d_<R-R>=0.400nm）的de Haas-van Alphen效应，研究了费米表面性质与导电和4-f电子杂化的关系。对于YbZn_3，<11>dHvA的频率范围为200 ~ 11000 T，回旋质量与YbSn_3相近。这些结果表明，YbS ...更多信息 YbSn_3和YbZn_3中的Yb离子均为<11>二价。UGa_2的dHvA频率范围为20 ~ 1300 T，回旋质量范围为0.3 ~ 3.3m_0。它们比YbSn_3和YbZn_3大<11>十倍。在UGa_2的最低频率振荡中观察到dHvA频率的场依赖性。这些结果表明，UGa_2中的5 f电子与导电电子有明显的杂化。我们还测量了LuAl 3中的de Haas-van Alphen效应，LuAl 3是YbAl 3的参考材料。观测到的频率范围为400 T ~ 23 kT，回旋有效质量范围为0.3 ~ 1 m ~ 0。用全势线性化APW方法计算了其能带结构。通过计算解释了观测结果的总体特征。在0.3K和15 T的磁场下，还没有观测到YbAl_3的dHvA效应。我们将尝试用稀释制冷机在较低温度下测量YbAl_3的dHvA效应。少

Valence fluctuation and heavy Fermion phenomena are observed in ytterbium and uranium compounds that have the nearest neighbor distance d_<R-R> between rare-earth ions smaller than some critical value, nearly equal to 0.45nm. The decrease in d_<R-R> is expected to increase hybridization between conduction electrons and 4-f electrons of rare-earth ions. In the present work we have measured the de Haas-van Alphen effect of YbZn_<11> (d_<R-R>=0.569nm), YbSn_3 (d_<R-R>=0.468nm), YbBi_2 (d_<R-R>=0.420nm), YbAl3 (d_<R-R>=0.420nm) and UGa_2 (d_<R-R>=0.400nm) to investigate the dependence of the Fermi surface properties on the hybridization between conduction and 4-f electrons The results for YbSn_3 show that the dHvA frequencies range from 60T to 3000T and the cyclotron masses from 0.13m_0 to 0.44m_0, where m_0 is the free electron mass. For YbZn_<11> the dHvA frequencies range from 200T to 11000T and the cyclotron masses are nearly the same as those of YbSn_3. These results indicate that YbS … More n_3 is a compensated metal and Yb ions in YbSn_3 and YbZn_<11> are divalent. The dHvA frequencies of UGa_2 range from 20T to 1300T.The observed cyclotron masses range from 0.3m_0 to 3.3m_0. They are larger than those of YbSn_3 and YbZn_<11> by a factor of ten. Field dependence ofthe dHvA frequency is observed in the lowest frequency oscillations in UGa_2. These results indicate that the 5f electrons in UGa_2 hybridize appreciably with the conduction electrons. We have also measured the de Haas-van Alphen effect in LuAl3, which is a reference material for YbAl3. Observed frequencies range from 400 T to 23 kT.The observed cyclotron effective masses range from 0.3m0 to 1m0. A band structure calculation was carried out by a full potential linearized APW method. The gross feature of the observed results was explained by the calculation. The measurement of YbAl3 has not been observed at 0.3K in magnetic fields as high as 15T.We will try to measure the dHvA effect of YbAl_3 in lower temperatures using dilution refrigerator. Less