Ko te whanonga o ngā rārangi Mohr me ngā whitiki papatahi i roto i te pūtaiao o te pūtaiao me te ahupūngao matū e kiia nei ko te "Magic Angle" twisted bilayer graphene (TBLG) kua kukume i te aro nui mai i ngā kaipūtaiao, ahakoa he maha ngā āhuatanga e tautohetohehia ana. I roto i tētahi rangahau hou i whakaputaina i roto i te puka Science Progress, i kitea e Emilio Colledo me ngā kaipūtaiao i te Tari Ahupūngao me te Pūtaiao Rauemi i te United States me Japan te superconductivity me te whakataurite i roto i te graphene twisted bilayer. Ko te āhua o te Mott insulator he koki hurihuri tata ki te 0.93 nekehanga. He 15% te iti ake o tēnei koki i te koki "magic koki" (1.1°) i tatauhia i roto i te rangahau o mua. E whakaatu ana tēnei rangahau he nui ake te whānuitanga "magic koki" o te graphene twisted bilayer i te mea i whakaarohia i mua.
He nui ngā mōhiotanga hou e whakaratohia ana e tēnei rangahau hei whakamārama i ngā āhuatanga matū kaha i roto i te graphene paparanga-rua miro mō ngā tono i roto i te ahupūngao matū. E whakamārama ana ngā tohunga ahupūngao i te "Twistronics" ko te koki miro whanaunga i waenga i ngā paparanga van der Waals e tata ana hei whakaputa i ngā roopu moiré me ngā roopu papatahi i roto i te graphene. Kua noho tēnei ariā hei tikanga hou, ahurei hoki mō te whakarerekē nui me te whakarite i ngā āhuatanga taputapu i runga i ngā rauemi rua-ahu hei whakatutuki i te rere o te iahiko. Ko te pānga whakamiharo o "Twistronics" i whakaatuhia i roto i ngā mahi paionia a ngā kairangahau, e whakaatu ana i te wā e whakarārangihia ana ngā paparanga graphene papatahi e rua ki te koki miro "koki makutu" o θ=1.1±0.1°, ka puta he roopu papatahi rawa.
I roto i tēnei rangahau, i roto i te graphene paparanga-rua takahuri (TBLG), kua whakakīia te wāhanga whakamātao o te microstrip tuatahi (āhuatanga hanganga) o te superlattice i te "koki makutu". I whakatauhia e te rōpū rangahau he Mott insulator tēnei (he insulator me ngā āhuatanga superconducting) e whakaatu ana i te superconductivity i ngā taumata doping teitei ake me te iti iho. E whakaatu ana te hoahoa wāhanga i te superconductor pāmahana teitei i waenga i te pāmahana whakawhiti superconducting (Tc) me te pāmahana Fermi (Tf). Nā tēnei rangahau i arahi ki te hiahia nui me te tautohetohe ariā mō te hanganga roopu graphene, te āhua me ngā pūnaha semiconductor "Magic Angle" tāpiri. Ki te whakataurite ki te pūrongo ariā taketake, he onge te rangahau whakamātautau, ā, kua tīmata noa. I roto i tēnei rangahau, i whakahaerehia e te rōpū ngā inenga tuku i runga i te graphene paparanga-rua takahuri "koki makutu" e whakaatu ana i ngā āhua whakamātao me te superconducting e tika ana.
Ko te koki whakapiko ohorere o te 0.93 ± 0.01, he 15% te iti iho i te "Magic Angle" kua whakatūria, koinei hoki te mea iti rawa i pūrongohia tae noa ki tēnei rā, ā, e whakaatu ana i ngā āhuatanga superconducting. E whakaatu ana ēnei hua ka puta te āhua hononga hou i roto i te "Magic Angle" miro-rua graphene, he iti iho i te "magic angle" tuatahi, i tua atu i te microstrip tuatahi o te graphene. Hei hanga i ēnei taputapu graphene miro-rua "magic horn", i whakamahia e te tīma he huarahi "haehae me te whakarārangi". Ko te hanganga i waenganui i ngā paparanga boron nitride hexagonal (BN) kua whakakīia; he tauira ki roto i te āhua Hall rod me ngā waea maha e honoa ana ki ngā hononga taha Cr/Au (chromium/koura). Ko te taputapu graphene miro-rua "Magic Angle" katoa i hangaia ki runga i te paparanga graphene i whakamahia hei kuaha o muri.
Ka whakamahia e ngā kaipūtaiao ngā tikanga raka paerewa o te au tika (DC) me te au tauutuutu (AC) hei ine i ngā taputapu i roto i ngā tioata HE4 me te HE3 kua papua. I tuhia e te tīma te whanaungatanga i waenga i te ātete roa (Rxx) o te taputapu me te whānuitanga o te ngaohiko kuaha whānui (VG) ā, i tatauhia te papa aukume B i te pāmahana o te 1.7K. I kitea te kore taurite o te kōhao irahiko iti hei āhuatanga tūturu o te taputapu graphene paparua takahuri "Magic Angle". E ai ki ngā pūrongo o mua, i tuhia e te tīma ēnei hua, ā, i whakamāramahia ngā pūrongo kua tino kawe hiko tae noa ki tēnei wā. Ko te "Magic Angle" āhuatanga ka takahuri i te koki torsion iti rawa o te taputapu graphene paparua. Mā te tirotiro tata atu i te tūtohi pā Landau, i whiwhi ngā kairangahau i ētahi āhuatanga whakamiharo.
Hei tauira, ko te tihi i te haurua o te whakakī me te whakahekenga rua o te taumata Landau e rite ana ki ngā āhua whakamātao rite-Moment i kitea i mua. I whakaatu te tīma i te pakaru o te ōritetanga o te awaawa hurihuri tata SU(4) me te hanganga o te mata Fermi āhua-matūriki hou. Heoi, me tirotirohia ngā taipitopito. I kitea hoki te āhua o te superconductivity, i piki ake ai te Rxx (ātete roa), he rite ki ngā rangahau o mua. I tirotirohia e te tīma te pāmahana tino nui (Tc) o te wāhanga superconducting. Nā te mea kāore i whiwhihia he raraunga mō te tāpiringa pai o ngā superconductors i roto i tēnei tauira, i whakaarohia e ngā kaipūtaiao he pāmahana tino nui tae atu ki te 0.5K. Heoi, ka kore e whai hua ēnei taputapu kia taea ra ano e rātou te tiki raraunga mārama mai i te āhua superconducting. Hei tirotiro atu i te āhua superconducting, i inehia e ngā kairangahau ngā āhuatanga ngaohiko-auau (VI) e whā-mutunga o te taputapu i ngā kiato kawe rerekē.
Ko te ātete i whiwhihia e whakaatu ana ka kitea te au nui i runga i te whānuitanga kiato nui ake, ā, e whakaatu ana i te pehi o te au nui ina whakamahia he papa aukume whakarara. Hei whiwhi māramatanga ki te whanonga i kitea i roto i te rangahau, i tatauhia e ngā kairangahau te hanganga roopu Moir o te taputapu graphene miro-rua "Magic Angle" mā te whakamahi i te tauira Bistritzer-MacDonald me ngā tawhā kua whakapaitia. Ki te whakatauritea ki te tataunga o mua o te koki "Magic Angle", kāore te roopu Moire pūngao iti i tatauhia i wehea mai i te roopu pūngao teitei. Ahakoa he iti ake te koki miro o te taputapu i te koki "magic angle" i tatauhia i hea atu, he āhuatanga kei te taputapu e hono kaha ana ki ngā rangahau o mua (te whakamarumaru Mort me te superconductivity), i kitea e ngā tohunga ahupūngao he mea ohorere, he mea taea hoki.
Whai muri i te arotakenga anō i te whanonga i ngā kiato nui (te maha o ngā āhua e wātea ana i runga i ia pūngao), ka honoa ngā āhuatanga i kitea e ngā kaipūtaiao ki ngā āhua whakamātao hou e puta ake ana. I te heke mai, ka whakahaerehia he rangahau taipitopito ake mō te kiato o ngā āhua (DOS) hei mārama ki te āhua tauhou o te whakamātao me te whakatau mēnā ka taea te whakarōpū hei wai hurihuri kuantum. I tēnei ara, i kitea e ngā kaipūtaiao te superconductivity tata ki te āhua whakamātao rite ki a Mox i roto i tētahi taputapu graphene paparanga-rua miro me te koki miro iti (0.93°). E whakaatu ana tēnei rangahau ahakoa i ngā koki iti me ngā kiato teitei, he rite tonu te pānga o te hononga irahiko ki ngā āhuatanga o te moiré. I te heke mai, ka akohia ngā awaawa miro o te wāhanga whakamātao, ā, ka akohia he wāhanga superconducting hou i te pāmahana iti iho. Ka honoa ngā rangahau whakamātautau me ngā mahi ariā hei mārama ki te takenga mai o tēnei whanonga.
Wā tuku: Oketopa-08-2019