Quantum Vortex Core and Missing Pseudogap in the Multiband BCS-BEC Crossover Superconductor FeSe
Quantum Vortex Core and Missing Pseudogap in the Multiband BCS-BEC Crossover Superconductor FeSe
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DOI：
10.1103/physrevlett.122.077001
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发表时间：
2019-02-21
影响因子：
8.6
通讯作者：
Matsuda, Y.
中科院分区：
文献类型：
--
作者：
Hanaguri, T.;Kasahara, S.;Matsuda, Y.
FeSe是Bardeen-Cooper-Schrieffer玻色-爱因斯坦凝聚过渡区的超导体，其超导能隙尺寸和超导转变温度Tc与费米能级相当。在这种情况下，涡旋束缚态应该是量子化的，并且在Tc以上的预形成对可以在准粒子激发谱中产生赝能隙。我们进行了光谱成像扫描隧道显微镜来寻找这些功能。我们在涡旋附近发现了类似Friedel的振荡，这表明了量子化能级，而没有检测到赝能隙。这些明显相互矛盾的意见可能与铁硒的多波段性质。
FeSe is argued as a superconductor in the Bardeen-Cooper-Schrieffer Bose-Einstein condensation crossover regime where the superconducting gap size and the superconducting transition temperature T-c are comparable to the Fermi energy. In this regime, vortex bound states should be well quantized and the preformed pairs above T-c may yield a pseudogap in the quasiparticle-excitation spectrum. We performed spectroscopic-imaging scanning tunneling microscopy to search for these features. We found Friedel-like oscillations near the vortex, which manifest the quantized levels, whereas the pseudogap was not detected. These apparently conflicting observations may be related to the multiband nature of FeSe.