De Haas-van Alphen effect in uranium and ytterbium Compounds

在稀土离子之间的最近邻距离d_<R-R>小于某个临界值，几乎等于0.45nm的镱和铀化合物中观察到价态波动和重费米子现象。d_<R-R>的减小有望增加稀土离子的传导电子和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）、YbAl3 （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传导电子和4-f电子杂化的关系。YbSn_3的dHvA频率范围为60T ~ 3000T，旋转加速器质量范围为0.13m_0 ~ 0.44m_0，其中m_0为自由电子质量。YbZn_<11>时，dHvA频率在200T ~ 11000T之间，回旋加速器质量与YbSn_3基本相同。结果表明，YbSn_3和YbZn_<11>中的Yb离子是二价的。UGa_2的dHvA频率范围为20T ~ 1300T。观测到的回旋加速器质量在0.3m_0到3.3m_0之间。它们比YbSn_3和YbZn_<11>的体积大十倍。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5f电子与传导电子发生了明显的杂化。我们还测量了LuAl3中的de Haas-van Alphen效应，LuAl3是YbAl3的参考材料。观测频率范围从400t到23kt。观测到的回旋加速器有效质量在0.3m0 ~ 1m0之间。采用全电位线性化APW方法进行了带结构计算。计算结果解释了观测结果的总体特征。在高达15T的磁场中，在0.3K下还没有观察到YbAl3的测量。我们将尝试用稀释冰箱在较低温度下测量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