Strongly correlated superconductor with polytypic 3D Dirac points
Strongly correlated superconductor with polytypic 3D Dirac points
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DOI：
10.1038/s41535-020-00268-4
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发表时间：
2019-09
影响因子：
5.7
通讯作者：
S. Borisenko;V. Bezguba;A. Fedorov;Y. Kushnirenko;V. Voroshnin;Mihai I. Sturza;S. Aswartham;A. Yaresko
中科院分区：
文献类型：
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作者：
S. Borisenko;V. Bezguba;A. Fedorov;Y. Kushnirenko;V. Voroshnin;Mihai I. Sturza;S. Aswartham;A. Yaresko
拓扑超导体应该能够为量子计算提供必要的成分，但实现起来非常具有挑战性。铁基超导体中的自旋-轨道相互作用使氮族元素的p态和铁的d态之间的能隙非常接近费米能级，并且这种p态最近已被实验探测到。密度泛函理论预测在FeTe 1 − xSex的这个能隙中存在拓扑表面态，使其成为一种有吸引力的候选材料。在这里，我们使用基于同步加速器的角分辨光电子能谱和能带结构计算来证明FeTe 1 −xSex（x= 0.45）是一种超导的3D狄拉克半金属，拥有I型和II型狄拉克点，并且它的电子结构在拓扑上仍然是平凡的。我们发现，FeTe 1 − xSex中的反向带隙可能通过进一步增加Te含量来实现，但强相关性使其减小到亚meV大小，使得实验检测该带隙和相应的拓扑表面态非常具有挑战性，更不用说与费米能级的精确匹配了。另一方面，p-d-d和d-d-d相互作用导致了费米能级处极平带的形成，表明它与IBS中的高Tc超导机制密切相关。
Topological superconductors should be able to provide essential ingredients for quantum computing, but are very challenging to realize. Spin–orbit interaction in iron-based superconductors opens the energy gap between thep-states of pnictogen andd-states of iron very close to the Fermi level, and suchp-states have been recently experimentally detected. Density-functional theory predicts existence of topological surface states within this gap in FeTe1−xSexmaking it an attractive candidate material. Here we use synchrotron-based angle-resolved photoemission spectroscopy and band structure calculations to demonstrate that FeTe1−xSex(x= 0.45) is a superconducting 3D Dirac semimetal hosting type-I and type-II Dirac points and that its electronic structure remains topologically trivial. We show that the inverted band gap in FeTe1−xSexcan possibly be realized by further increase of Te content, but strong correlations reduce it to a sub-meV size, making the experimental detection of this gap and corresponding topological surface states very challenging, not to mention exact matching with the Fermi level. On the other hand, thep–dandd–dinteractions are responsible for the formation of extremely flat band at the Fermi level pointing to its intimate relation with the mechanism of high-Tcsuperconductivity in IBS.