论文标题
$ \ mathrm {cecoin_ {5}} $中的量子特定探针
Element-specific probe of quantum criticality in $\mathrm{CeCoIn_{5}}$
论文作者
论文摘要
采用X射线吸收光谱（XAS）和X射线磁性圆形二色性（XMCD）的元素灵敏度，我们研究了重型费米昂超导体Cecoin $ _5 $中的价值和磁顺序。我们探测CE中F-电子的自旋群体和CO中D-Electrons中的自旋群体，这是温度（低至0.1 K）和磁场（最高6 t）的函数。从XAS中，我们发现CE $^{4+} $在低温下的明显贡献和CE Valence低于5 K的明确温度依赖性，表明价值增强，这表明存在附近量子关键点（QCP）。我们观察到与磁场没有显着的相应变化。 XMCD显示CE仅在6 t处变得薄弱的信号。KramersDoubleT CE $^{3+} $的这种分裂明显小于独立但筛选的离子的预期，表明强烈的抗铁磁对相互作用。 Cecoin $ _5 $中超导性的非常规特征在超导过渡的极为大的热步骤中显而易见。
Employing the elemental sensitivity of x-ray absorption spectroscopy (XAS) and x-ray magnetic circular dichroism (XMCD), we study the valence and magnetic order in the heavy fermion superconductor CeCoIn$_5$. We probe spin population of the f-electrons in Ce and d-electrons in Co as a function of temperature (down to 0.1 K) and magnetic field (up to 6 T). From the XAS we find a pronounced contribution of Ce$^{4+}$ component at low temperature and a clear temperature dependence of the Ce valence below 5 K, suggesting enhanced valence fluctuations, an indication for the presence of a nearby quantum critical point (QCP). We observe no significant corresponding change with magnetic field. The XMCD displays a weak signal for Ce becoming clear only at 6 T. This splitting of the Kramers doublet ground state of Ce$^{3+}$ is significantly smaller than expected for independent but screened ions, indicating strong antiferromagnetic pair interactions. The unconventional character of superconductivity in CeCoIn$_5$ is evident in the extremely large specific heat step at the superconducting transition.
