DFT+DMFT研究钴的交换相互作用及其对hcp和fcc相竞争的影响
DFT+DMFT study of exchange interactions in cobalt and their implications for the competition of hcp and fcc phases
AI总结：
本研究采用DFT+DMFT方法计算钴的交换相互作用，发现hcp相较fcc相具有更大的自旋刚度和更高的居里温度，从而解释了实验中观察到的居里温度附近hcp相的“复活”现象。
摘要：
我们在密度泛函理论加动力学平均场理论（DFT+DMFT）框架下，重新考虑了顺磁相中fcc和hcp钴的磁性。利用最近提出的顺磁相交换相互作用计算方法，我们提取了fcc和hcp钴的交换相互作用参数，并表明hcp相具有更大的自旋刚度，与实验数据一致，显示出更强的铁磁性倾向。相应地，hcp相的DMFT居里温度高于fcc相。预计fcc相在远低于钴居里温度时磁有序的消失会影响其结构稳定性，并使该相在实验居里温度附近在能量上不利。这可能解释了在钴居里温度附近观察到的hcp相的“复活”现象，该现象在最近的扰动角关联研究[Sci. Rep. {\f 12}, 10054 (2022)]的实验结果中被观察到。
英文摘要：
We reconsider magnetic properties of fcc and hcp cobalt within the density functional theory plus dynamical mean-field theory (DFT+DMFT) approach in the paramagnetic phase. Using recently proposed approach of calculation of exchange interactions in paramagnetic phase, we extract exchange interaction parameters of fcc and hcp cobalt and show that the hcp phase possesses larger spin stiffness, in agreement with the experimental data, showing stronger tendency to ferromagnetism. Accordingly, the DMFT Curie temperature of the hcp phase appears to be higher, than that of the fcc phase. The disappearance of magnetic order in the fcc phase well below the cobalt Curie temperature is expected to affect its structural stability and make this phase energetically unfavourable near the experimental Curie temperature. This may explain the "revival" of the hcp phase near the Curie temperature of cobalt, observed in the recent experimental results of perturbed angular correlation study [Sci. Rep. {\bf 12}, 10054 (2022)].
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