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首页> 外文期刊>Physical Review X >Fermi Surface with Dirac Fermions in CaFeAsF Determined via Quantum Oscillation Measurements
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Fermi Surface with Dirac Fermions in CaFeAsF Determined via Quantum Oscillation Measurements

机译：通过量子振荡测量测定CafeSF中的狄拉克码头的费米表面

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Despite the fact that 1111-type iron arsenides hold the record transition temperature of iron-based superconductors, their electronic structures have not been studied much because of the lack of high-quality single crystals. In this study, we comprehensively determine the Fermi surface in the antiferromagnetic state of CaFeAsF, a 1111 iron-arsenide parent compound, by performing quantum oscillation measurements and band-structure calculations. The determined Fermi surface consists of a symmetry-related pair of Dirac electron cylinders and a normal hole cylinder. From analyses of quantum-oscillation phases, we demonstrate that the electron cylinders carry a nontrivial Berry phase π . The carrier density is of the order of 10 ? 3 per Fe. This unusual metallic state with the extremely small carrier density is a consequence of the previously discussed topological feature of the band structure which prevents the antiferromagnetic gap from being a full gap. We also report a nearly linear-in- B magnetoresistance and an anomalous resistivity increase above about 30?T for B ∥ c , the latter of which is likely related to the quantum limit of the electron orbit. Intriguingly, the electrical resistivity exhibits a nonmetallic temperature dependence in the paramagnetic tetragonal phase ( T 118 K ), which may suggest an incoherent state. Our study provides a detailed knowledge of the Fermi surface in the antiferromagnetic state of 1111 parent compounds and moreover opens up a new possibility to explore Dirac-fermion physics in those compounds.
机译：尽管1111型铁砷化物保持了铁基超导体的记录过渡温度，但由于缺乏高质量的单晶，它们的电子结构尚未大量研究。在这项研究中，通过进行量子振荡测量和带结构计算，我们全面地确定CafeSF的反铁磁状态下的费米表面，通过进行量子振荡测量和带结构计算。确定的费米表面包括与对称的对称的狄拉克电子汽缸和正常孔圆筒组成。根据量子振荡阶段的分析，我们证明电子汽缸携带非竞争浆膜π。载体密度为10？每零3。这种具有极小载流子密度的不寻常的金属状态是先前讨论了带结构的拓扑特征的结果，这防止了防冻差距是完全间隙。我们还报告了几乎线性的磁阻和异常电阻率，其高于B + C的增加，后者可能与电子轨道的量子极限有关。有趣的是，电阻率表现出在顺磁四方相（T> 118K）中的非金属温度依赖性，这可能表明一种不连贯的状态。我们的研究提供了1111个母体化合物的反铁磁性状态的Fermi表面的详细知识，而且开辟了新的可能性探索这些化合物中的Dirac-Fermion物理学。

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