Layer-cake 2D superconductivity

doi:10.1126/science.abd4225

GSTDTAP > 气候变化

DOI	10.1126/science.abd4225
	Layer-cake 2D superconductivity
	Leslie M. Schoop
	2020-10-09
发表期刊	Science
出版年	2020
英文摘要	Materials science historically has had an immense impact on humanity, as entire periods of time, such as the Bronze or Iron ages, have been named after materials ([ 1 ][1]). In the modern era, a new class of materials called quantum materials has started to affect people's lives. Quantum materials are broadly defined as materials whose electronic or magnetic behavior cannot be explained by classical physics ([ 2 ][2]). Discoveries of quantum materials with distinct or improved properties are often followed by a surge of research, resulting in either the discovery of new physics, or in applications, such as in low–power consumption electronics, sensing, photodetection, high-speed electronics, or quantum information science ([ 3 ][3]). On page 231 in this issue, Devarakonda et al. report the synthesis of a highly interesting quantum material ([ 4 ][4]), which may facilitate the study of quantum effects that so far have been obscured. Superconductors are a class of fascinating quantum materials with properties that inspired dreams of applications without power loss, such as high-speed, levitating trains. These dreams have in part been realized through development of materials that superconduct at high enough temperatures for cooling of liquid nitrogen instead of helium, which is expensive and sparse ([ 5 ][5]). The discovery of these high–critical temperature superconductors created a fascinating puzzle. The superconductivity of these materials is “unconventional,” meaning that the mechanism is not fully understood. One way to shine light on the physics behind the superconductivity is to reduce the dimensionality of the materials. Two-dimensional (2D) superconductors simplify the problem and also offer access to many other unsolved mysteries of condensed matter physics. These include the Berezenskii-Kosterlitz-Thouless (BKT) transition ([ 6 ][6]), which is an early example of a “topological” phase transition whose discovery was awarded the 2016 Nobel Prize in Physics. Although materials that exhibit 2D superconductivity are known, imperfections in the crystals have impeded study. Because 2D materials are only a few atoms thick, they often suffer from degradation upon exposure to air or from defects that result from exfoliation. For these reasons, 2D materials are usually manually encapsulated with protecting layers, typically boron nitride ([ 7 ][7]). To create a system for studying the pure physics of 2D superconductivity, a known material can be made as pure as possible, or a new material can be designed. Although purifying materials is costly and time-consuming, developing new materials presents a host of other challenges. The discovery of clean 2D superconductivity in Ba6Nb11S28 by Devarakonda et al. opens the door to a better understanding of 2D superconductivity and its associated quantum phenomena. ![Figure][8] Protected 2D layers Alternating layers of superconducting NbS2 and a Ba3NbS5 spacer allow high electron mobility in the NbS2 while also protecting it. This creates a “layer cake”– like structure that permits clean superconducting behavior. GRAPHIC: N. DESAI/ SCIENCE ADAPTED FROM ([ 4 ][4]) The material is an intrinsic heterostructure consisting of alternating layers of the 2D superconductor NbS2 and an electronically uninteresting spacer layer, Ba3NbS5 (see the figure). Think of the material as a layer cake with a thin layer of chocolate repeatedly inserted between thicker layers of cake. The chocolate is the superconductor (NbS2) and the dough is the spacer layer that protects the chocolate from cracking or being attacked by air or moisture. Because of this protection, the NbS2 layer exhibits much cleaner 2D superconductivity than a single, unprotected layer. This feature is manifested by the mobility of electrons within the protected NbS2 layer, which is three orders of magnitude higher than what has been reported in the unprotected counterpart. In addition, the BKT transition can be observed in Ba6Nb11S28. because of the high purity of the NbS2 layers. The beauty of this material also lies in the natural growth of the heterostructure, as if the aforementioned layer cake could be baked by merely mixing the chocolate and batter in a bowl and putting the mixture in an oven with the two components naturally separating during the baking process. This makes the synthesis process much less labor-intensive than adding each layer manually, as is necessary when protecting 2D crystals with boron nitride. Because of the ease of synthesis, different types of layered materials may be developed where the 2D layers are naturally protected by their environment. The 2D layer would not always have to be a superconductor. Different types of quantum materials are also possible. One example might be topological insulators, which belong to a class of quantum materials with promise for several applications, one example being quantum computing ([ 8 ][9]). The authors' discovery suggests a much simpler alternative to exfoliated nanodevice fabrication. The key question is whether this strategy will easily extend to other materials beyond Ba6Nb11S28. 1. [↵][10]1. N. A. Spaldin , VSH-Bull. no. 2 (August 2017), p. 11. 2. [↵][11]1. B. Keimer, 2. J. E. Moore , Nat. Phys. 13, 1045 (2017). [OpenUrl][12][CrossRef][13][PubMed][14] 3. [↵][15]1. Y. Tokura, 2. M. Kawasaki, 3. N. Nagaosa , Nat. Phys. 13, 1056 (2017). [OpenUrl][16][CrossRef][17] 4. [↵][18]1. A. Devarakonda et al ., Science 370, 231 (2020). [OpenUrl][19][CrossRef][20] 5. [↵][21]1. R. J. Cava , J. Am. Ceram. Soc. 83, 5 (2000). [OpenUrl][22][CrossRef][23] 6. [↵][24]1. A. M. Goldman , in 40 Years of Berezinskii–Kosterlitz–Thouless Theory (World Scientific, 2013), pp. 135–160. 7. [↵][25]1. K. S. Novoselov et al ., Science 353, aac9439 (2016). [OpenUrl][26][Abstract/FREE Full Text][27] 8. [↵][28]1. S.D. Sarma, 2. M. Freedman, 3. C. Nayak , npj Quantum Inf. 1, 1 (2015). [OpenUrl][29] Acknowledgments: The author acknowledges support by the Gordon and Betty Moore Foundation through grant GBMF9064. [1]: #ref-1 [2]: #ref-2 [3]: #ref-3 [4]: #ref-4 [5]: #ref-5 [6]: #ref-6 [7]: #ref-7 [8]: pending:yes [9]: #ref-8 [10]: #xref-ref-1-1 "View reference 1 in text" [11]: #xref-ref-2-1 "View reference 2 in text" [12]: {openurl}?query=rft.jtitle%253DNat.%2BPhys.%26rft.volume%253D13%26rft.spage%253D1045%26rft_id%253Dinfo%253Adoi%252F10.1038%252Fnphys4302%26rft_id%253Dinfo%253Apmid%252F10649993%26rft.genre%253Darticle%26rft_val_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Ajournal%26ctx_ver%253DZ39.88-2004%26url_ver%253DZ39.88-2004%26url_ctx_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Actx [13]: /lookup/external-ref?access_num=10.1038/nphys4302&link_type=DOI [14]: /lookup/external-ref?access_num=10649993&link_type=MED&atom=%2Fsci%2F370%2F6513%2F170.atom [15]: #xref-ref-3-1 "View reference 3 in text" [16]: {openurl}?query=rft.jtitle%253DNat.%2BPhys.%26rft.volume%253D13%26rft.spage%253D1056%26rft_id%253Dinfo%253Adoi%252F10.1038%252Fnphys4274%26rft.genre%253Darticle%26rft_val_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Ajournal%26ctx_ver%253DZ39.88-2004%26url_ver%253DZ39.88-2004%26url_ctx_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Actx [17]: /lookup/external-ref?access_num=10.1038/nphys4274&link_type=DOI [18]: #xref-ref-4-1 "View reference 4 in text" [19]: {openurl}?query=rft.jtitle%253DScience%26rft.stitle%253DScience%26rft.aulast%253DDevarakonda%26rft.auinit1%253DA.%26rft.volume%253D370%26rft.issue%253D6513%26rft.spage%253D231%26rft.epage%253D236%26rft.atitle%253DClean%2B2D%2Bsuperconductivity%2Bin%2Ba%2Bbulk%2Bvan%2Bder%2BWaals%2Bsuperlattice%26rft_id%253Dinfo%253Adoi%252F10.1126%252Fscience.aaz6643%26rft.genre%253Darticle%26rft_val_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Ajournal%26ctx_ver%253DZ39.88-2004%26url_ver%253DZ39.88-2004%26url_ctx_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Actx [20]: /lookup/external-ref?access_num=10.1126/science.aaz6643&link_type=DOI [21]: #xref-ref-5-1 "View reference 5 in text" [22]: {openurl}?query=rft.jtitle%253DJ.%2BAm.%2BCeram.%2BSoc.%26rft.volume%253D83%26rft.spage%253D5%26rft_id%253Dinfo%253Adoi%252F10.1111%252Fj.1151-2916.2000.tb01142.x%26rft.genre%253Darticle%26rft_val_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Ajournal%26ctx_ver%253DZ39.88-2004%26url_ver%253DZ39.88-2004%26url_ctx_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Actx [23]: /lookup/external-ref?access_num=10.1111/j.1151-2916.2000.tb01142.x&link_type=DOI [24]: #xref-ref-6-1 "View reference 6 in text" [25]: #xref-ref-7-1 "View reference 7 in text" [26]: {openurl}?query=rft.jtitle%253DScience%26rft.stitle%253DScience%26rft.aulast%253DNovoselov%26rft.auinit1%253DK.%2BS.%26rft.volume%253D353%26rft.issue%253D6298%26rft.spage%253Daac9439%26rft.epage%253Daac9439%26rft.atitle%253D2D%2Bmaterials%2Band%2Bvan%2Bder%2BWaals%2Bheterostructures%26rft_id%253Dinfo%253Adoi%252F10.1126%252Fscience.aac9439%26rft_id%253Dinfo%253Apmid%252F27471306%26rft.genre%253Darticle%26rft_val_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Ajournal%26ctx_ver%253DZ39.88-2004%26url_ver%253DZ39.88-2004%26url_ctx_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Actx [27]: /lookup/ijlink/YTozOntzOjQ6InBhdGgiO3M6MTQ6Ii9sb29rdXAvaWpsaW5rIjtzOjU6InF1ZXJ5IjthOjQ6e3M6ODoibGlua1R5cGUiO3M6NDoiQUJTVCI7czoxMToiam91cm5hbENvZGUiO3M6Mzoic2NpIjtzOjU6InJlc2lkIjtzOjE2OiIzNTMvNjI5OC9hYWM5NDM5IjtzOjQ6ImF0b20iO3M6MjI6Ii9zY2kvMzcwLzY1MTMvMTcwLmF0b20iO31zOjg6ImZyYWdtZW50IjtzOjA6IiI7fQ== [28]: #xref-ref-8-1 "View reference 8 in text" [29]: {openurl}?query=rft.jtitle%253Dnpj%2BQuantum%2BInf.%26rft.volume%253D1%26rft.spage%253D1%26rft.genre%253Darticle%26rft_val_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Ajournal%26ctx_ver%253DZ39.88-2004%26url_ver%253DZ39.88-2004%26url_ctx_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Actx
领域	气候变化 ; 资源环境
URL	查看原文
引用统计
文献类型	期刊论文
条目标识符	http://119.78.100.173/C666/handle/2XK7JSWQ/298086
专题	气候变化资源环境科学
推荐引用方式 GB/T 7714	Leslie M. Schoop. Layer-cake 2D superconductivity[J]. Science,2020.
APA	Leslie M. Schoop.(2020).Layer-cake 2D superconductivity.Science.
MLA	Leslie M. Schoop."Layer-cake 2D superconductivity".Science (2020).