论文标题
频段结构，超导性和多型ausn $ _4 $
Band structure, superconductivity and polytypism in AuSn$_4$
论文作者
论文摘要
Orthorhombic化合物AUSN4在组成上与Dirac节点ARC半学PTSN $ _4 $相似。 AUSN $ _4 $与PTSN $ _4 $相反，超导为t $ _c $ = 2.35 K的临界温度。最近的测量值为AUSN $ _4 $中的准二维超导行为的最新测量指示。在这里，我们通过扫描隧道显微镜（STM）和Angular分辨光发射光谱（ARPES）介绍了状态超导密度和AUSN $ _4 $的带结构的测量值。费米表面的不同部分的超导差距值分布在Δ0= 0.4 meV左右，该差距接近但大于$δ= $δ= $ 1.76KBT $ _C $。我们观察到表面的隧道电导中的超导特征，直至温度比散装TC大约20％。用密度功能理论（DFT）计算的带结构很好地遵循ARPES的结果。晶体结构提出了两个可能的SN层堆叠，提供了两个近乎退化的多型。这使AUSN $ _4 $成为一个相当独特的案例，具有三维电子带结构，但属性将其组合成低维分层化合物的案例。
The orthorhombic compound AuSn4 is compositionally similar to the Dirac node arc semimetal PtSn$_4$. AuSn$_4$ is, contrary to PtSn$_4$, superconducting with a critical temperature of T$_c$ = 2.35 K. Recent measurements present indications for quasi two-dimensional superconducting behavior in AuSn$_4$. Here we present measurements of the superconducting density of states and the band structure of AuSn$_4$ through Scanning Tunneling Microscopy (STM) and Angular Resolved Photoemission Spectroscopy (ARPES). The superconducting gap values in different portions of the Fermi surface are spread around Δ0 = 0.4 meV, which is close to but somewhat larger than $Δ=$ 1.76kBT$_c$ expected from BCS theory. We observe superconducting features in the tunneling conductance at the surface up to temperatures about 20% larger than bulk Tc. The band structure calculated with Density Functional Theory (DFT) follows well the results of ARPES. The crystal structure presents two possible stackings of Sn layers, giving two nearly degenerate polytypes. This makes AuSn$_4$ a rather unique case with a three dimensional electronic band structure but properties ressembling those of low dimensional layered compounds.
