Coherence and Spin correlations in Kondo Semiconductors

通过中子散射、muSR和低温磁测量，对广岛大学生长的CeNiSn、Ce7Ni3和YbB12单晶的相干性和自旋相关性进行了研究。中子散射研究(1)在12t的磁场中研究了CeNiSn的自旋激发，在4 meV的能量峰的场依赖性可以追溯到比热的场依赖性。发现这种准一维相关性对CeNiSn中的间隙形成至关重要。(2) Ce7Ni3在4 kbar临界压力附近的非弹性散射可以用ω /T的通用函数来描述。(3) YbB12在14 meV处的自旋激发强度表现出很强的q依赖性，在（111）.2处有一个极大值。μ子自旋弛豫研究(I) CeNil-xCuxSn在x=0.06附近表现出非磁-磁跃迁。(2) Ce7Ni3的muSR结果表明，在1.8K和0.7K下，SDW发生了一级跃迁，二级跃迁。Ce离子的磁矩方向偏离c轴。低温下量子临界行为的研究（一）CeNi0.95Cu0.05Sn的比热除以温度和磁化率继续增加，直至0.025K。(2)在0.4 GPa压力下，Ce7Ni3在0.5K以上比热下的非费米液体行为是0.2K以下费米液体行为的交叉。

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.