Cobalt $L$-edge x-ray absorption spectra (XAS) and x-ray magnetic circular dichroism (XMCD) of ${\mathrm{CoS}}_2$ have been measured at low temperature (4 K) in order to characterize the electronic and magnetic structure with a significant improvement in resolution as compared with previous measurements. The branching ratio of $L_3$ and $L_2$ x-ray absorption near-edge spectra was found to be consistent with a low-spin configuration ($S=1/2$). A total magnetic moment $〈m〉=0.78{\mu }_B$/Co atom with the orbital part $〈m_l〉=0.049{\mu }_B$ has been obtained from the XMCD signal, consistent with the nearly half-metallic character of ${\mathrm{CoS}}_2$ and with the itinerant nature of the ferromagnetism. The behavior under pressure of ${\mathrm{CoS}}_2$ was studied by Co $K$-edge XAS and XMCD experiments performed up to a pressure of about 30 GPa using diamond-anvil cell at a temperature of 10 K. No evidence of structural phase transition was observed, while the intensity of the XMCD signal was found to decrease continuously for increasing pressures, becoming negligible in the $8\sim 10$ GPa pressure range, a fact consistent with the collapse of itinerant ferromagnetic ordering. The gradual change in the electronic and magnetic structure upon application of pressure was also monitored by the near-edge XAS evolution, found to be in agreement with full multiple-scattering calculations under uniform contraction of distances, and by the blue-shift of the $K$-edge energy. The Co $K$-edge energy was found to shift to higher energies (up to 0.64 eV at 30 GPa) and a change of slope was observed at pressures around 5 GPa that may correspond to the disappearance of half-metallicity, in agreement with previous studies.

中文翻译：

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压力下CoS2中流动铁磁性的崩溃：X射线吸收光谱研究

钴 $\mathrm{大号}$的X射线边缘X射线吸收光谱（XAS）和X射线磁圆二向色性（XMCD） ${\mathrm{CoS}}_{\mathrm{2个}}$为了表征电子和磁性结构，与以前的测量相比，在高分辨率（4 K）下进行了测量，我们已经对它们进行了表征。的分支比${\mathrm{大号}}_3$ 和 ${\mathrm{大号}}_{\mathrm{2个}}$ 发现x射线吸收近边缘光谱与低自旋配置一致（$\mathrm{小号}=\mathrm{1个}/\mathrm{2个}$）。总磁矩$〈米〉=0.78{\mu }_{乙}$/ Co原子与轨道部分 $〈{米}_{升}〉=0.049{\mu }_{乙}$ 是从XMCD信号获得的，与 ${\mathrm{CoS}}_{\mathrm{2个}}$并具有铁磁性的流动性。压力下的行为${\mathrm{CoS}}_{\mathrm{2个}}$ 由Co研究 $ķ$边缘XAS和XMCD实验在10 K的温度下使用金刚石-砧室电池在高达30 GPa的压力下进行。未观察到结构相变的证据，同时发现XMCD信号的强度随着增加而连续降低压力，可以忽略不计 $8〜10$ GPa压力范围，与迭代铁磁有序崩溃的事实一致。电子和磁性结构在施加压力后的逐渐变化也通过近边缘XAS演化进行了监测，发现与均匀距离收缩下的完全多次散射计算以及通过蓝色偏移引起的变化相吻合。$ķ$边缘能源。公司$ķ$与以前的研究一致，发现边缘能量转移到更高的能量（在30 GPa时高达0.64 eV），并且在5 GPa左右的压力下观察到了斜率变化，这可能对应于半金属性的消失。