Kuye kwenziwa intuthuko ekufundweni kokunyakaza okusheshayo kwama-Weil quasiparticles alawulwa yi-laser

Kuye kwenziwa intuthuko ekufundweni kokunyakaza okusheshayo kwama-Weil quasiparticles alawulwa yi-ama-laser

Eminyakeni yamuva nje, ucwaningo lwethiyori nolwezokuhlola ngezimo ze-quantum ze-topological kanye nezinto ze-quantum ze-topological selube yisihloko esishisayo emkhakheni we-physics yezinto ezihlanganisiwe. Njengomqondo omusha wokuhlukaniswa kwezinto, ukuhleleka kwezinto, njengokulingana, kuwumqondo oyisisekelo ku-physics yezinto ezihlanganisiwe. Ukuqonda okujulile kwe-topology kuhlobene nezinkinga eziyisisekelo ku-physics yezinto ezihlanganisiwe, njengesakhiwo esiyisisekelo se-elekthronikhiizigaba ze-quantum, ukuguquka kwesigaba se-quantum kanye nokuvuselelwa kwezinto eziningi ezingashukumi ezigabeni ze-quantum. Ezintweni ze-topological, ukuhlangana phakathi kwamazinga amaningi enkululeko, njengama-electron, ama-phononi kanye ne-spin, kudlala indima ebalulekile ekuqondeni nasekulawuleni izakhiwo zezinto. Ukuvuselelwa kokukhanya kungasetshenziswa ukuhlukanisa phakathi kokuxhumana okuhlukene nokulawula isimo sezinto, futhi ulwazi mayelana nezakhiwo eziyisisekelo zomzimba zezinto, ukuguquka kwesigaba sokwakheka, kanye nezimo ezintsha ze-quantum lungatholakala. Njengamanje, ubudlelwano phakathi kokuziphatha kwe-macroscopic kwezinto ze-topological eziqhutshwa yinsimu yokukhanya kanye nesakhiwo sazo se-athomu esincane kanye nezakhiwo ze-elekthronikhi sekube umgomo wocwaningo.

Ukuziphatha kwempendulo ye-photoelectric yezinto ze-topological kuhlobene eduze nesakhiwo sayo se-elekthronikhi esincane kakhulu. Kuma-semi-metals e-topological, i-carrier excitation eduze kwendawo yokuhlangana kwebhendi ibucayi kakhulu ezicini zomsebenzi wamagagasi esistimu. Ucwaningo lwezimo ze-optical ezingezona eziqondile kuma-semi-metals e-topological lungasisiza ukuthi siqonde kangcono izakhiwo zomzimba zezimo ezijabulisayo zesistimu, futhi kulindeleke ukuthi le miphumela ingasetshenziswa ekwakhiweni kweamadivayisi opticalkanye nomklamo wamaseli elanga, okuhlinzeka ngezinhlelo zokusebenza ezingaba khona esikhathini esizayo. Isibonelo, ku-Weyl semi-metal, ukumunca i-photon yokukhanya okujikelezile okune-polarized kuzokwenza ukuthi ukujikeleza kuphenduke, futhi ukuze kuhlangatshezwane nokulondolozwa komfutho we-angular, ukukhushulwa kwama-electron ezinhlangothini zombili ze-Weyl cone kuzosatshalaliswa ngendlela engalingani eceleni kwendlela yokusabalalisa ukukhanya okujikelezile okune-polarized, okubizwa ngokuthi umthetho wokukhetha i-chiral (Isithombe 1).

Ucwaningo lwethiyori lwezimo ze-optical ezingezona eziqondile zezinto ze-topological luvame ukusebenzisa indlela yokuhlanganisa ukubalwa kwezakhiwo zesimo somhlabathi kanye nokuhlaziywa kokulingana. Kodwa-ke, le ndlela inamaphutha athile: ayinalo ulwazi oluguquguqukayo lwesikhathi sangempela lwabathwali abajabule esikhaleni se-momentum kanye nesikhala sangempela, futhi ayikwazi ukusungula ukuqhathanisa okuqondile nendlela yokuthola yokuhlola exazululwe ngesikhathi. Ukuhlangana phakathi kwama-electron-phononi nama-photon-phononi akunakucatshangelwa. Futhi lokhu kubalulekile ukuze kwenzeke izinguquko ezithile zesigaba. Ngaphezu kwalokho, lokhu kuhlaziywa kwethiyori okusekelwe ku-perturbation theory akukwazi ukubhekana nezinqubo zomzimba ngaphansi kwensimu yokukhanya enamandla. Ukulingisa kwe-time-dependent density functional molecular dynamics (TDDFT-MD) okusekelwe ezimisweni zokuqala kungaxazulula izinkinga ezingenhla.

Muva nje, ngaphansi kokuqondiswa komcwaningi uMeng Sheng, umcwaningi we-postdoctoral uGuan Mengxue kanye nomfundi we-doctoral uWang En we-SF10 Group ye-State Key Laboratory of Surface Physics ye-Institute of Physics ye-Chinese Academy of Sciences/Beijing National Research Center for Concentrated Matter Physics, ngokubambisana noSolwazi uSun Jiatao we-Beijing Institute of Technology, basebenzise isofthiwe yokulingisa i-excited state dynamics simulation TDAP. Izici zokuphendula ze-quastiparticle excitation ku-ultrafast laser ohlotsheni lwesibili lwe-Weyl semi-metal WTe2 ziyahlolwa.

Kuye kwaboniswa ukuthi ukuvusa okukhethayo kwabathwali eduze kwephuzu le-Weyl kunqunywa ukulingana kwe-atomic orbital kanye nomthetho wokukhetha ukuguquka, ohlukile kumthetho wokukhetha ojwayelekile we-spin we-chiral excitation, futhi indlela yawo yokuvusa ingalawulwa ngokushintsha isiqondiso se-polarization sokukhanya oku-linearly polarized kanye namandla e-photon (Isithombe 2).

Ukuvusa okungalingani kwabathwali kubangela ama-photocurrents ngezindlela ezahlukene endaweni yangempela, okuthinta isiqondiso kanye nokulingana kokushelela kwe-interlayer yesistimu. Njengoba izakhiwo ze-topological ze-WTe2, njengenani lamaphuzu e-Weyl kanye nezinga lokuhlukana endaweni ye-momentum, zincike kakhulu ekuhlanganiseni kwesistimu (Isithombe 3), ukuvusa okungalingani kwabathwali kuzoletha ukuziphatha okuhlukile kwama-Weyl quastiparticles endaweni ye-momentum kanye nezinguquko ezihambisanayo ezakhiweni ze-topological zesistimu. Ngakho-ke, ucwaningo luhlinzeka ngomdwebo wesigaba ocacile wokuguqulwa kwesigaba se-phototopological (Isithombe 4).

Imiphumela ikhombisa ukuthi i-chirality ye-carrier excitation eduze kwe-Weyl point kufanele inakwe, futhi kufanele kuhlaziywe izakhiwo ze-athomu ze-orbital zomsebenzi wamagagasi. Imiphumela yalezi zibili iyafana kodwa indlela yokusebenza ihlukile ngokusobala, enikeza isisekelo semfundiso yokuchaza ubunye bamaphuzu e-Weyl. Ngaphezu kwalokho, indlela yokubala eyasetshenziswa kulolu cwaningo ingaqonda ngokujulile ukusebenzisana okuyinkimbinkimbi kanye nokuziphatha okuguquguqukayo emazingeni e-athomu kanye ne-elekthronikhi ngesikali sesikhathi esisheshayo kakhulu, yembule izindlela zazo ze-microphysical, futhi kulindeleke ukuthi ibe ithuluzi elinamandla locwaningo lwesikhathi esizayo ngezimo ze-optical ezingezona eziqondile ezintweni ze-topological.

Imiphumela ikumagazini i-Nature Communications. Umsebenzi wocwaningo usekelwa yi-National Key Research and Development Plan, i-National Natural Science Foundation kanye ne-Strategic Pilot Project (Isigaba B) se-Chinese Academy of Sciences.

ISITHOMBE 1.a. Umthetho wokukhetha i-chirality yamaphuzu e-Weyl anophawu lwe-chirality oluhle (χ=+1) ngaphansi kokukhanya okugoqekile okuyisiyingi; Ukukhathazeka okukhethiwe ngenxa yokulingana kwe-athomu ye-orbital endaweni ye-Weyl ka-b. χ=+1 ekukhanyeni okugoqekile okuku-inthanethi

ISITHOMBE 2. Umdwebo wesakhiwo se-athomu se-a, Td-WTe2; b. Isakhiwo sebhendi eduze kobuso be-Fermi; (c) Isakhiwo sebhendi kanye neminikelo ehlobene yama-orbital e-athomu asatshalaliswe ngemigqa ephezulu yokulinganisa esifundeni saseBrillouin, imicibisholo (1) kanye (2) imelela ukuvusa eduze noma kude namaphuzu e-Weyl, ngokulandelana; d. Ukwandiswa kwesakhiwo sebhendi eceleni kwesiqondiso se-Gamma-X

ISITHOMBE 3.ab: Ukunyakaza okuhlobene kwezingqimba zokuqondisa ukukhanya okuhlukaniswe ngomugqa eceleni kwe-A-axis kanye ne-B-axis yekristalu, kanye nemodi yokunyakaza ehambisanayo kuyaboniswa; C. Ukuqhathaniswa phakathi kokulingisa okufundiswayo kanye nokubuka kokuhlola; de: Ukuvela kokulinganisa kwesistimu kanye nesikhundla, inombolo kanye nezinga lokuhlukaniswa kwamaphuzu amabili aseduze e-Weyl endizeni ye-kz=0

UMFANELO 4. Ushintsho lwesigaba se-phototopological ku-Td-WTe2 lwamandla e-photon okukhanya okune-polarized linearly (?) ω) kanye nomdwebo wesigaba esincike esiqondisweni se-polarization (θ)