标题： 磁场在重费米子化合物YbCo$_2$Zn$_{20}$中的影响 显示英文标题

标题： Effect of magnetic field in heavy-fermion compound YbCo$_2$Zn$_{20}$

摘要： 对重费米子化合物YbCo$_2$Zn$_{20}$的多晶样品进行非弹性中子散射实验，以获得对基态及其磁场响应的微观见解。 在零磁场下300 mK时，非弹性响应包括两个特征：准弹性散射和0.6 meV处的尖峰。 随着温度升高，在2.1 meV附近出现一个宽峰，而准弹性响应变宽，0.6 meV处的峰变得不清晰。 施加磁场后，在1 T以上准弹性响应显著变宽，0.6 meV处的峰在磁场下变得模糊。 非弹性光谱中的峰及其温度变化可归因于提出的晶体场模型${{\Gamma}_6}$ - ${{\Gamma}_8}$ - ${{\Gamma}_7}$，整体分裂小于3 meV。 观察到的准弹性响应及其在磁场下的快速展宽表明，重电子态来源于基态双线态，并在YbCo$_2$Zn$_{20}$中受到外部磁场的强烈抑制。 显示英文摘要

摘要： Inelastic neutron scattering experiments on poly crystalline sample of heavy-fermion compound YbCo$_2$Zn$_{20}$ were carried out in order to obtain microscopic insights on the ground state and its magnetic field response. At zero field at 300 mK, inelastic response consists of two features: quasielastic scattering and a sharp peak at 0.6 meV. With increasing temperature, a broad peak comes up around 2.1 meV, whereas quasielastic response gets broader and the peak at 0.6 meV becomes unclear. By applying magnetic field, the quasielastic response exhibits significant broadening above 1 T, and the peak at 0.6 meV is obscure under fields. The peaks in inelastic spectra and its temperature variation can be ascribed to the suggested crystal-field model of ${{\Gamma}_6}$ - ${{\Gamma}_8}$ - ${{\Gamma}_7}$ with the overall splitting of less than 3 meV. The observed quasielastic response and its rapid broadening with magnetic field indicates that the heavy-electron state arises from the ground state doublets, and are strongly suppressed by external field in YbCo$_2$Zn$_{20}$.