NiS_(2-x)Se_x在x=1.00附近的反铁磁量子相变

Antiferromagnetic quantum phase transition near x=1.00 in NiS_(2-x)Se_x system

针对NiS2-xSex系统在x=1.00附近发生的反铁磁量子相变,制备了一系列NiS2-xSex(x=0.96,0.98,1.00,1.05,1.10和1.20)多晶样品,对其结构、磁性质和电阻率进行了系统的观测.结果发现:样品磁化率-温度关系呈现典型的强关联电子系统特征;与铜氧化物超导体相类似,它们的电阻率-温度关系在很宽的温区内(50—300K)呈现线性行为;对于x=0.98,1.00样品,低温下(3—30K)电阻率满足ρ(T)∝T3/2,呈现非费米液体行为,而在x=1.10,1.20样品中的ρ(T)又呈现费米液体预言的T2关系.根据与量子相变行为相关的反铁磁量子涨落对结果进行了讨论.

There may be an antiferromagnetic quantum phase transition near x = 1.00 in NiS2- x Sex system. The polycrystalline samples of NiS2- x Sex （x = 0.96, 0.98, 1.00, 1.05, 1.10 and 1.20） were prepared by the solid state reaction method, and the measurements of their structure, magnetization and resistivity were carried out. It is found that the temperature dependence of susceptibility is typical characteristic of a strongly correlated electron system. Similar to high Tc superconductors, the relationship between resistivity and temperature displays a linear behavior in a wide temperature range from 50 to 300 K. For NiS2-xSex（x = 0.98 and 1.00） samples, its p（T） is proportional to T3/2 at lower temperatures （3-30 K）, which shows a non-Fermi-liquid behavior. But for NiS2-x Sex （x = 1.10 and 1.20） samples, its p（T） is proooportional to T2 at lower temperatures （3-30 K）, which shown the Fermi-liquid behavior. The antiferromagnetic quantum spin fluctuation related to quantum phase transition is discussed in detail.