Discovery of AgxTaS2 superconductor with stage-3 structure
Discovery of AgxTaS2 superconductor with stage-3 structure
复制标题
三级结构AgxTaS2超导体的发现
DOI：
10.1088/2053-1583/abbac1
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发表时间：
2020
期刊：
影响因子：
5.5
通讯作者：
H. Kaiju and J. Nishii
中科院分区：
文献类型：
--
作者：
Z. Khurelbaatar;M. Fujioka;T. Shibuya;S. Demura;S. Adachi;Y. Takano;M. Jeem;M. Ono;H. Kaiju and J. Nishii
通过界面工程，如离子插层，我们可以调整和优化过渡金属二卤化物及其器件的性能。在本研究中，我们首次对AgxTas2单晶的第三阶段进行了实验研究，并在3.8K发现了它的超导电性。采用一种简单的水浸工艺，通过从低级结构中脱出银离子，获得了第三级结构。此外，我们发展了一个确定晶体结构的通用堆积规则，它可以预测AgxTa2的任何高阶阶段结构。超导转变温度从阶段2的1.7K提高到阶段3的3.8K，是原始的Ta2(0.8K)的4倍多。这种增强归因于费米能级上态密度的增加，这是用密度泛函理论计算的。此外，水浸工艺将阶段2重建为阶段3结构，同时恶化了其结晶度。这种结构扭曲是第二阶段电荷密度波被抑制的潜在原因之一，导致超导电性在结构退化的情况下得到增强。
Through interfacial engineering, such as ion intercalation, we can tune the properties and optimize the performance of transition metal dichalcogenides and their devices. In this study, we present the first-time experimental investigations of stage 3 of Ag x TaS 2 single crystal, and its superconductivity was discovered at 3.8 K. Highly crystalline stage 1 and 2 were prepared by a proton-driven ion-introduction method. A simple water-soaking process was employed to achieve the stage-3 structure by deintercalation of Ag ions from lower stage structures. Besides, we developed a general stacking rule to determine the crystal structure, and it can predict any higher-order stage structure of Ag x TaS 2. The superconducting transition temperature was enhanced from 1.7 K for a stage-2 structure to 3.8 K for a stage-3 structure, which is more than four times that of the pristine TaS 2 (0.8 K). This enhancement is attributed to the increase in density of states at the Fermi level, which was calculated by density functional theory. Also, the water-soaking process reconstructs the stage-2 into the stage-3 structure while deteriorating its crystallinity. Such a structural distortion is one of the potential reasons for the suppression of charge density wave in stage-2, resulting in the enhancement of superconductivity despite the structural degradation.