Coherence and Spin correlations in Kondo Semiconductors

本文用中子散射、μ SR和低温磁测量方法研究了近藤半导体中的相干和自旋关联.实验材料为广岛大学生长的CeNiSn，Ce_7 Ni_3和YbB_（12）单晶.这种准一维的相关性被认为是必不可少的间隙形成CeNiSn。(2)在临界压力4kbar附近，Ce_7 Ni_3的非弹性散射可用一个普适函数ω/T来描述。(3)在14 meV处，YbB_（12）的自旋激发强度与q有很强的依赖关系，在（111）处有一个尖锐的最大值。2. μ子自旋弛豫研究（I）CeNil-xCuxSn在x=0.06附近出现非磁-磁跃迁。(2)Ce_7 Ni_3的muSR结果表明，Ce_7 Ni_3在1.8K发生了一级SDW相变，在0.7K发生了二级相变，Ce离子的磁矩方向偏离c轴。3.量子临界行为的低温研究（I）CeNi_0.95Cu_0.05Sn的比热和磁化率在0.025K以下继续增加。(2)在0.4GPa的压力下，在高于0.5K的比热下观察到的Ce 7 Ni 3的非费米液体行为与低于0.2K的费米液体行为是交叉的。

The coherence and spin correlations in Kondo semiconductors have been studied by neutron scattering, muSR and low-temperature magnetic measurements on single crystals of CeNiSn, Ce7Ni3 and YbB12 grown at Hiroshima University.1.Neutron scattering study(1) The spin excitaion in CeNiSn was studied in magnetic fields up to 12 T.The field dependence of the peak at an energy of 4 meV traces that of the specific heat. This quasi-one dimensional correlation is found to be essential for gap formation in CeNiSn.(2) The inelastic scattering from Ce7Ni3 near the critical pressure of 4 kbar can be described by a universal function of omega/T.(3) The intensity of spin excitaion of YbB12 at 14 meV shows strong q dependence with a sharp maximum at (111).2.Muon spin relaxation study(I) CeNil-xCuxSn exhibits a nonmagnetic-magnetic transition near x=0.06.(2) The muSR results on Ce7Ni3 indicates the first-order SDW transition at 1.8K and second-order transition at 0.7K.The direction of the magnetic moment of Ce ions tilts from the c axis.3.Low-temperature study of quantum critical behavior(I) Both the specific heat divided by temperature and magnetic susceptibility of CeNi0.95Cu0.05Sn continue to increase down to 0.025K.(2) Non-Fermi liquid behavior in the specific heat of Ce7Ni3 observed above 0.5K under a pressure of 0.4 GPa is found to be a crossover to the Fermi liquid behavior below 0.2K.