Co(S1-xSex)2系统中的铁磁量子相变

针对Co(S_1-xSe_x)₂系统在x=0.11附近发生的铁磁金属到顺磁金属相变，制备了一系列不同Se替代浓度的多晶样品.通过对其结构和电阻率-温度ρ(T)关系的系统观测，结果发现，样品铁磁相变温度T_C随着Se替代浓度x值的增加，以(1-x)^1/2关系单调下降，其二级铁磁相变转变为一级相变关键词：量子相变自旋量子涨落1-xSe_x)₂')" href="#">Co(S_1-xSe_x)₂

Ferromagnetic quantum phase transition in Co(S1-xSex)2 system

In Co(S_1-xSe_x)₂ system, a transition from ferromagnetic to paramagnetic state occurs near x = 0.11. In order to research the physical properties of the samples near this transition, polycrystalline samples of Co(S_1-xSe_x)₂ (0.0≤x≤0.16) were prepared. And their structure and resistivity were measured. It is found that the ferromagnetic transition temperature T_C is suppressed by Se doping in the relation T_C～(1-x)^1/2. And the ferromagnetic phase transition goes from the second to the first order. The temperature dependence of resistivity, ρ(T), shows a Fermi-liquid behavior, ρ(T)=ρ₀+AT², in Co(S_1-xSe_x)₂ (x<0.08) samples, while the non-Fermi liquid behavior of ρ(T) occurs in the samples near a critical concentration x=0.11. It is suggested that the phase transition near x=0.11 is a quantum phase transition, and the quantum critical spin fluctuation at zero temperature results in non-Fermi liquid behavior.