Studies of non-fermi liquid behavior in heavy fermion compounds by specific heat measurements under high pressure and magnetic field

为了研究Ce重费米子系统中的非费米液体行为，测量了六方结构的Ce_xLa_a&lt；1-x&Gt；Pd_2Al_3(x=0~1.0)的电阻率和比热。在0.5K到4.2K之间，还测量了高达5T的磁场中的比热。本工作的主要结果是：1.磁比热除以温度C_m/T，在较宽的Ce浓度范围内(x=0.7以下)呈现非费米液体行为(-InT依赖)，此时反铁磁转变消失。对于x≦0.15时，通过施加指示恢复费米液态的磁场，抑制了C_m/T中的对数发散。通过积分C_m/T和T计算的磁熵在磁场中没有增强，这表明非费米液体行为不是由双通道近藤效应引起的。在x=0.3~0.7的宽Ce浓度范围内，Cm/T表现出惊人的相同的温度依赖关系。Ce_xLa_&lt；1-x&gt；Pd_2Al_3的这种浓度依赖特性在其他体系中是没有的。

To investigate the non-fermi liquid behavior in Ce heavy fermion systems, electrical resistivity and specific heat of Ce_xL.a_<1-x>Pd_2Al_3 (x = 0〜1.0) with hexagonal structure were measured down to 0.4K. Specific heat was also measured in magnetic fields up to 5T between 0.5 and 4.2K. The main results of this work are ;1. Magnetic specific heat divided by temperature, C_m/T, shows a non-fermi liquid behavior ( -InTdependence) in the wide Ce concentration range below x = 0.7, at which the antiferro-magnetic transition disappears.2. For x ≦ 0.15, the logarithmic divergence in C_m/T is suppressed by application of the magnetic fields indicating a recovery of the fermi-liquid states. Magnetic entropy calculated by integrating C_m/T with T is not enhanced in magnetic fields suggesting that the non-fermi liquid behavior could not arise from 2-channel Kondo effect.3. C_m/T exhibit surprisingly identical temperature dependence in the wide Ce concentration range between x = 0.3 and 0.7. Such concentration dependence characteristic of Ce_xLa_<1-x>Pd_2Al_3 has not been found in other systems.