Study on competition between the Kondo effect and intersite multipole interactions in cerium-lanthanum hexaborides

我们测量了六硼化铈镧的比热和弹性常数。我们已经证实，一个非磁性的状态是实现在Ce 0.5La 0.5B6在低温和低场。这种非磁性状态被磁场破坏，并诱导出有序状态。非磁性态的低温比热与T^（1.5）成正比。这表明非磁态不同于重费米子态。在Ce_（0.75）La_（0.25）B_6体系中还发现了一个新的磁性相（第IV相）。相IV的序参量尚未确定。我们发现，第Ⅳ相的Ce_（0.75）La_（0.25）B_6的比热与T_（^2）成正比。比热的这种行为特征与反铁磁状态相矛盾。

We have measured specific heat and elastic constants of cerium-lanthanum hexaborides. We have confirmed that a non-magnetic state is realized in Ce0.5La0.5B6 at low-temperatures and low fields. This non-magnetic state is destroyed by the fields, and an ordered state is induced. Low-temperature specific heat of the non-magnetic state is in proportion to T^(1.5). This indicates that the non-magnetic state is distinct from heavy Fermion state. We have also found that a new magnetic phase (Phase IV) in the Ce0.75La0.25B6 system. The order parameter of phase IV has not been identified yet. We have found that the specific heat of Ce0.75La0.25B6 in phase IV is in proportion to T^2. This behavioral feature of the specific heat is contradictory to an antiferro-magnetic state.