反铁磁NaFeAs中局域结构和自旋排列的~（57）Fe穆斯堡尔谱研究
A 57Fe Mössbauer Study Of Local Structure And Spin Arrangements In Antiferromagnetic NaFeAs
摘要：
对超导NaFeAs粉末晶体进行了详细的~（57）Fe穆斯堡尔谱测量。假设Fe ~（2+）离子位于畸变四面体（FeAs ~ 4）中，讨论了在顺磁温度范围（T > TN \approx 46 +/- 2 K）内记录的~（57）Fe谱。结果表明，结构转变（TS \approx 55 K）对铁原子的电子结构影响很小，而反铁磁有序（T =< TN）的发展引起57 Fe核电荷的重新分布.在低温范围内，光谱显示出扩散共振吸收结构，证明在57 Fe核处存在连续分布的超精细场HFe。这些光谱的形状可能与微区结构或相分离的形成有关。对所得分布p（HFe）的分析表明，穆斯堡尔谱在整个温度范围内给出了一致的和物理上合理的57 Fe超精细参数。
英文摘要：
Detailed 57Fe Mössbauer spectroscopy measurements on superconducting NaFeAs powder crystals have been performed. The 57Fe spectra recorded in the paramagnetic temperature range (T > TN \approx 46 +/- 2 K) were discussed supposing Fe2+ ions are located in distorted tetrahedral (FeAs4) polyhedra. Our results reveal that the structural transition (TS \approx 55 K) has a weak effect on the electronic structure of iron atoms while the development of the antiferromagnetic order (T =< TN) induces a redistribution of the charge at 57Fe nuclei. In the low-temperature range, the spectra show a diffuse resonance absorption structure which evidences for the existence of a continuous distribution of hyperfine fields HFe at 57Fe nuclei. The shape of these spectra can be related to the formation of a microdomain structure or phase separation. Analysis of the resulting distributions p(HFe) has shown that the Mössbauer spectra give consistent and physically reasonable 57Fe hyperfine parameters over the whole temperature range.
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