Non-Fermi Liquid phenomena in heavy-fermion Ce compounds

最近的神经元衍射实验表明，在<1-x>顺磁重费米子化合物CeRu_2Si_2的Ru位上取代Rh后的Ce（Ru_Rh_2）Si_2系统具有反铁磁有序度为0.05 × 0.3的无公度正弦结构（波数和力矩是沿着c轴）。因此，在本研究项目的第一步中，我们测量了电阻率，本系统的比热和磁化率。结果表明，在Neel温度下，重准粒子带沿c轴方向沿着发生费米面嵌套，费米面部分能隙开放。因此，我们得出结论，反铁磁性是由于自旋密度波（SDW）跃迁后的费米面嵌套。我们还测量了本系统在磁场中的电阻率、比热和磁化率。结果表明，差距崩塌，重费米子的费米面完全恢复到顺磁费米液态.在x=0.03的情况下，我们测量了电阻率和磁化率，这是在SDW和顺磁相之间的低临界浓度区. x=0.35，0.375和0.40时，处于高临界浓度区。当x=0.03时，测量了类费米液体的温度依赖性，磁化率与温度无关，低温下电阻率为cT^2。另一方面，对于x = 0.35，0.375和0.40的非费米液体的温度依赖性已被观察到：磁化率 * -ROO<T>和电阻率 * T。因此，它是建议，非费米液体相存在于该系统的高临界Rh浓度区的x *0.35。

Recent neuron diffraction experiment has shown that a system Ce(Ru_<1-x>Rh_2)Si_2, where Rh is substituted into the Ru site of paramagnetic heavy-fermion compound CeRu_2Si_2 with a large magnetic anisotropy along the c-axis, has an antiferromagnetic ordering for 0.05*x*0.3 with an incommensurate sinusoidal structure (the wave number and moment are along the c-axis).Thus, in the first step of this research project we measured the resistivity, specific heat and susceptibility of the present system. The results suggest that the Fermi-surface nesting occurs along the c-axis direction in the heavy quasi-particle band at the Neel temperature with Partial gap opening of the Fermi surface. Therefore, we conclude that the antiferromagnetism is due to the spin density wave (SDW) transition following the Fermi-surface nesting. We also measured the resistivity, specific heat and susceptibility of the present system in magnetic fields. The results suggest' that the gap collapse and the Fermi surface of the heavy fermion completely recovers into a paramagnetic Fermi liquid state.In the next step we measured the resistivity and susceptibility for .x=0.03, which is in the lower critical concentration region between the SDW and paramagnetic phases, . and for x=0.35, 0.375 and 0.40, which is in the higher critical concentration region. For x=0.03 Fermi-liquid like temperature dependence has been measured the susceptibility is temperature independent and the resistivity cc T^2 in the low temperature. On the other hand, for x = 0.35, 0.375 and 0.40 non-Fermi-liquid like temperature dependence has been observed : the susceptibility * -ROO<T> and the resistivity * T.Therefore, it is suggested that a non-Fermi-liquid phase exists in the higher critical Rh-concentration region of x *0.35 of this system.