Surface electronic structure and evidence of plain s-wave superconductivity in (Li0.8Fe0.2)OHFeSe
Surface electronic structure and evidence of plain s-wave superconductivity in (Li0.8Fe0.2)OHFeSe
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(Li0.8Fe0.2)OHFeSe表面电子结构和平面横波超导证据
DOI：
10.1103/physrevb.94.134502
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发表时间：
2016
影响因子：
3.7
通讯作者：
Feng D. L.
中科院分区：
文献类型：
--
作者：
Yan Y. J.;Zhang W. H.;Ren M. Q.;Liu X.;Lu X. F.;Wang N. Z.;Niu X. H.;Fan Q.;Miao J.;Tao R.;Xie B. P.;Chen X. H.;Zhang T.;Feng D. L.
是一种新发现的插层铁硒化物超导体，其温度高于40 K，远高于块状FeSe（8 K）。在这里，我们报告了低温扫描隧道显微镜（STM）的系统研究。我们观察到两种表面终端，即FeSe和表面。在FeSe表面，超导态完全带隙，具有双相干峰，并且观察到具有近分裂峰的涡核态。通过准粒子干涉（QPI）测量，我们清楚地观察到该点电子袋之间的袋内和袋间散射，以及连接点的散射的一些证据。施加磁场后，发现所有散射通道的 QPI 强度表现相似。此外，我们通过研究故意引入的杂质和固有缺陷来研究杂质对超导性的影响。我们观察到诸如 Cr 吸附原子之类的磁性杂质可以诱导带隙态并抑制超导性。然而，诸如锌吸附原子之类的非磁性杂质不会引起可见的带隙内态。同时，我们发现锌吸附原子可以在厚的 FeSe 薄膜中诱导带隙态，这被认为具有波配对对称性。我们的实验结果表明，它很可能是平波超导体，其阶次参数在所有费米表面截面上具有相同的符号。
is a newly discovered intercalated iron-selenide superconductor with aabove 40 K, which is much higher than theof bulk FeSe (8 K). Here we report a systematic study ofby low temperature scanning tunneling microscopy (STM). We observed two kinds of surface terminations, namely FeSe andsurfaces. On the FeSe surface, the superconducting state is fully gapped with double coherence peaks, and a vortex core state with split peaks nearis observed. Through quasiparticle interference (QPI) measurements, we clearly observed intra- and interpocket scatterings in between the electron pockets at thepoint, as well as some evidence of scattering that connectsandpoints. Upon applying the magnetic field, the QPI intensity of all the scattering channels are found to behave similarly. Furthermore, we studied impurity effects on the superconductivity by investigating intentionally introduced impurities and intrinsic defects. We observed that magnetic impurities such as Cr adatoms can induce in-gap states and suppress superconductivity. However, nonmagnetic impurities such as Zn adatoms do not induce visible in-gap states. Meanwhile, we show that Zn adatoms can induce in-gap states in thick FeSe films, which is believed to have an-wave pairing symmetry. Our experimental results suggest it is likely thatis a plain-wave superconductor, whose order parameter has the same sign on all Fermi surface sections.