Superconductivity wani abu ne na zahiri wanda juriyar lantarki na wani abu ke raguwa zuwa sifili a wani yanayi mai mahimmanci. Ka'idar Bardeen-Cooper-Schrieffer (BCS) bayani ne mai tasiri, wanda ke bayyana superconductivity a yawancin kayan aiki. Yana nuna cewa nau'ikan Cooper electron suna samuwa a cikin layin lu'ulu'u a yanayin zafi mai ƙarancin yawa, kuma cewa superconductivity na BCS ya fito ne daga danshinsu. Kodayake graphene kanta kyakkyawan mai sarrafa wutar lantarki ne, bai nuna superconductivity na BCS ba saboda hana hulɗar electron-phonon. Wannan shine dalilin da ya sa yawancin masu sarrafa "kyawawan" (kamar zinariya da jan ƙarfe) superconductors ne "mara kyau".
Masu bincike a Cibiyar Nazarin Kimiyyar Halittu ta Tsarin Hadaka (PCS) a Cibiyar Kimiyyar Asali (IBS, Koriya ta Kudu) sun ba da rahoton wata sabuwar hanyar da za a bi don cimma babban ƙarfin lantarki a cikin graphene. Sun cimma wannan nasarar ta hanyar gabatar da tsarin haɗin gwiwa wanda ya ƙunshi graphene da Bose-Einstein condensate mai girma biyu (BEC). An buga binciken a cikin mujallar 2D Materials.
Tsarin haɗin gwiwa wanda ya ƙunshi iskar gas ta lantarki (layin sama) a cikin graphene, wanda aka raba shi da haɗin Bose-Einstein mai girma biyu, wanda aka wakilta ta hanyar excitons kai tsaye (layin shuɗi da ja). An haɗa electrons da excitons a cikin graphene ta hanyar ƙarfin Coulomb.
(a) Dogara ga zafin jiki na gibin da ke cikin tsarin da bogolon ke jagoranta tare da gyaran zafin jiki (layin da aka ja) da kuma ba tare da gyaran zafin jiki ba (layin da aka ja). (b) Yanayin zafin jiki mai mahimmanci na canjin superconductor a matsayin aikin yawan condensate don hulɗar da bogolon ke jagoranta tare da (layin da aka ja) da kuma ba tare da (layin da aka ja) gyaran zafin jiki ba (baƙar fata). Layin da aka ja mai digo yana nuna zafin canjin BKT a matsayin aikin yawan condensate.
Baya ga yanayin da ke kewaye da iska, BEC wani lamari ne da ke faruwa a yanayin zafi mai ƙanƙanta. Wannan shine yanayi na biyar na matter da Einstein ya fara annabta a shekarar 1924. Samuwar BEC yana faruwa ne lokacin da ƙwayoyin halitta masu ƙarancin kuzari suka taru suka shiga yanayin makamashi ɗaya, wanda shine fanni na bincike mai zurfi a cikin kimiyyar lissafi mai rikitarwa. Tsarin Bose-Fermi mai haɗaka a zahiri yana wakiltar hulɗar Layer na electrons tare da Layer na bosons, kamar excitons na kai tsaye, exciton-polarons, da sauransu. Hulɗar tsakanin ƙwayoyin Bose da Fermi ta haifar da nau'ikan sabbin abubuwa masu ban sha'awa, waɗanda suka jawo hankalin ɓangarorin biyu. Ra'ayi na asali da na aikace-aikace.
A cikin wannan aikin, masu binciken sun ba da rahoton wani sabon tsarin superconducting a cikin graphene, wanda ya faru ne saboda hulɗar da ke tsakanin electrons da "bogolons" maimakon phonons a cikin tsarin BCS na yau da kullun. Bogolons ko Bogoliv quasiparticles sune abubuwan motsa jiki a cikin BEC, waɗanda ke da wasu halaye na barbashi. A cikin wasu jeri na sigogi, wannan tsarin yana ba da damar superconducting mai mahimmanci a cikin graphene ya kai har zuwa 70 Kelvin. Masu bincike sun kuma haɓaka sabuwar ka'idar BCS mai ƙananan ƙwayoyin cuta wacce ta mayar da hankali musamman kan tsarin da aka dogara da sabon graphene mai haɗaka. Tsarin da suka gabatar ya kuma annabta cewa kaddarorin superconducting na iya ƙaruwa tare da zafin jiki, wanda ke haifar da dogaro da zafin jiki mara monotonic na gibin superconducting.
Bugu da ƙari, bincike ya nuna cewa watsawar Dirac na graphene an kiyaye shi a cikin wannan tsari da bogolon ke jagoranta. Wannan yana nuna cewa wannan tsarin superconducting ya ƙunshi electrons tare da watsawar relativistic, kuma wannan lamari ba a bincika shi sosai a cikin kimiyyar lissafi mai rikitarwa ba.
Wannan aikin ya bayyana wata hanya ta cimma yanayin zafi mai zafi. A lokaci guda, ta hanyar sarrafa halayen condensate, za mu iya daidaita yanayin graphene mai ƙarfi. Wannan yana nuna wata hanya ta sarrafa na'urorin superconducting a nan gaba.
Lokacin Saƙo: Yuli-16-2021 
