arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 1207.3145cond-mat.supr-con
收藏

新型BiS2-based层状超导体Bi4O4S3

Novel BiS2-based layered superconductor Bi4O4S3

Yoshikazu Mizuguchi, Hiroshi Fujihisa, Yoshito Gotoh, Katsuhiro Suzuki, Hidetomo Usui, Kazuhiko Kuroki, Satoshi Demura, Yoshihiko Takano, Hiroki Izawa, Osuke Miura

摘要:

奇异的超导性经常在具有层状(二维)晶体结构的材料中发现。低维度可以影响电子结构,并且可以实现高转变温度(Tc)和/或非常规的超导机制。作为标准的例子,我们现在有两种类型的高温超导体。第一类是铜氧化物超导体,其晶体结构基本上由间隔层堆叠而成第二组是Fe基超导体,其也具有间隔层和超导Fe 2An 2的堆叠结构。(An = P,As,Se,Te)层。5 -13在两种系统中,通过优化间隔层结构,例如,各种组成元素,间隔厚度,以及相对于超导层的载流子掺杂水平。在这方面,为了实现比Cu氧化物和Fe基超导体更高的Tc超导性,需要实现层状超导体的新原型的发现。在这里,我们展示了一个新的铋氧硫化物层状化合物Bi 4 O 4S 3的超导电性。晶体结构分析表明,该超导体具有由Bi_4O_4(SO_4)_1-x和Bi_2S_4层堆叠而成的层状结构,母体化合物(x = 0)为Bi_6O_8S_5。能带计算表明,Bi_4 O_4S_3(x = 0.5)是金属性的,而Bi_6 O_8 S_5(x = 0)则是带绝缘体。此外,Bi_4 O_4S_3的费米能级正好位于Bi_2层中Bi_6p轨道的分态密度的峰值位置。BiS 2层是层状超导体的一种基本结构,它为层状超导体家族提供了另一种普适性类,为低维超导体的物理和化学研究开辟了一个新的领域。

英文摘要:

Exotic superconductivity has often been discovered in materials with a layered (two-dimensional) crystal structure. The low dimensionality can affect the electronic structure and can realize high transition temperatures (Tc) and/or unconventional superconductivity mechanisms. As standard examples, we now have two types of high-Tc superconductors. The first group is the Cu-oxide superconductors whose crystal structure is basically composed of a stacking of spacer (blocking) layers and superconducting CuO2 layers.1-4 The second group is the Fe-based superconductors which also possess a stacking structure of spacer layers and superconducting Fe2An2 (An = P, As, Se, Te) layers.5-13 In both systems, dramatic enhancements of Tc are achieved by optimizing the spacer layer structure, for instance, a variety of composing elements, spacer thickness, and carrier doping levels with respect to the superconducting layers. In this respect, to realize higher-Tc superconductivity, other than Cu-oxide and Fe-based superconductors, the discovery of a new prototype of layered superconductors needs to be achieved. Here we show superconductivity in a new bismuth-oxysulfide layered compound Bi4O4S3. Crystal structure analysis indicates that this superconductor has a layered structure composed of stacking of Bi4O4(SO4)1-x and Bi2S4 layers; the parent compound (x = 0) is Bi6O8S5. Band calculation suggests that Bi4O4S3 (x = 0.5) is metallic while Bi6O8S5 (x = 0) is a band insulator with Bi3+. Furthermore, the Fermi level for Bi4O4S3 is just on the peak position of the partial density of states of the Bi 6p orbital within the BiS2 layer. The BiS2 layer is a basic structure which provides another universality class for layered superconducting family, and this opens up a new field in the physics and chemistry of low-dimensional superconductors.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

↑