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[[Vol. 19]Visualizing superconductive coupling over atomic steps_ WPI-MANA.pdf](https://mdr.nims.go.jp/filesets/2bde94af-c1b6-48e9-a660-79cbf0351008/download)

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International Center for Materials Nanoarchitectonics (WPI-MANA)

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[[Research Highlights Vol.19] Visualizing superconductive coupling over atomic steps](https://mdr.nims.go.jp/datasets/51628caf-9def-4101-88fb-8480a472d23c)

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2022/04/04 10:20 Visualizing superconductive coupling over atomic steps| MANAhttps://www.nims.go.jp/mana/research/highlights/vol19.html 1/2Previous  Index  NextResearch Highlights[Vol. 19]Visualizing superconductive coupling over atomic steps27 Feb, 2015Scanning tunnelling microscopy imaging under differing magnetic fields givesfundamental insights into the behavior of supercurrents and vortices on thesurface of indium-doped silicon films.Figure : Scientists at the International Center for MaterialsNanoarchitectonics have uncovered how supercurrents flow overatomic steps and terraces on indium-covered silicon surface.Vortices trapped at the atomic steps change their characters fromPearl to Josephson vortices (from A to C). These reflect change instrength of Josephson coupling between the neighboring terraces.Superconductors have effectively zero resistance and act as perpetual carriers of electric currentwith no need for a connected power source. As such they have many applications in electronics.One of the thinnest two-dimensional materials ever created, called Si(111)-(√7 x √3)-In –individualindium metal atoms added to a silicon surface - recently surprised scientists with itssuperconducting abilities. The race is now on to find out how and why this silicon surface iscapable of superconductivity, as well as what uses it may have.Takashi Uchihashi and co-workers at the International Center for Materials Nanoarchitectonics,Tsukuba, together with scientists across Japan, have now uncovered the underlying structures andthe behavior of currents on the surface of Si(111)-(√7 x √3)-In which provide clues to itssuperconductivity.The silicon surface comprises individual terraces separated by steps measuring the height of asingle atom (‘atomic steps’). These steps could potentially interrupt, or decouple, neighboringterraces and break the current flowing over large surfaces. Uchihashi and his team used ascanning tunnelling microscope in order to verify how superconductivity occurs in the presence ofatomic steps and terraces. The team applied different magnetic fields, which influenced thestrength of the current and the presence of associated vortices.https://www.nims.go.jp/mana/research/highlights/vol18.htmlhttps://www.nims.go.jp/mana/research/highlights/index.htmlhttps://www.nims.go.jp/mana/research/highlights/vol20.html2022/04/04 10:20 Visualizing superconductive coupling over atomic steps| MANAhttps://www.nims.go.jp/mana/research/highlights/vol19.html 2/2By taking a series of images of the silicon, the team uncovered a pattern of supercurrent vorticespresent on the silicon surface. Two vortex types were present. Pearl vortices were present on theterrace surfaces, and appeared as bright round features in the images. However, at the atomicsteps the vortices appeared to become trapped and altered in character. These elongated‘Josephson vortices’ give evidence that the atomic steps work as so-called Josephson junctions,allowing coupling to occur across stepped terraces and enabling supercurrents to flow. The ideawas firmly established with the help of microscopic theoretical calculations.Reference"Imaging Josephson vortices on the surface superconductor using a scanning tunnellingmicroscope"Shunsuke Yoshizawa, Howon Kim, Takuto Kawakami, Yuki Nagai, Tomonobu Nakayama, Xiao Hu,Yukio Hasegawa, and Takashi UchihashiJournal : Physical Review Letters (highlighted as an Editors' Suggestion) (2014).DOI : 10.1103/PhysRevLett.113.247004AffiliationsInternational Center for Materials Nanoarchitectonics (WPI-MANA), National Institute for MaterialsScience (NIMS), Namiki 1-1, Tsukuba, Ibaraki 305-0044, JapanContact informationInternational Center for Materials Nanoarchitectonics(WPI-MANA)National Institute for Materials Science1-1 Namiki, Tsukuba, Ibaraki 305-0044 JapanPhone: +81-29-860-4710E-mail: mana-pr[AT]ml.nims.go.jphttps://samurai.nims.go.jp/profiles/nakayama_tomonobu?locale=enhttps://samurai.nims.go.jp/profiles/hu_xiao?locale=enhttps://samurai.nims.go.jp/profiles/uchihashi_takashi?locale=enhttps://journals.aps.org/prl/abstract/10.1103/PhysRevLett.113.247004