Inqubekelaphambili yenziwe ocwaningweni lokuhamba okusheshayo kwe-Weil quasiparticles elawulwa yiama-laser
Eminyakeni yamuva nje, ucwaningo lwethiyori nokuhlola lwezifunda ze-topological quantum kanye nezinto ze-topological quantum sekuyisihloko esishisayo emkhakheni we-condensed matter physics. Njengomqondo omusha wokuhlukaniswa kwezinto, ukuhleleka kwe-topological, njengokulinganisa, kuwumqondo oyisisekelo kufiziksi yento efingqiwe. Ukuqonda okujulile kwe-topology kuhlobene nezinkinga eziyisisekelo ku-condensed matter physics, njengesakhiwo se-elekthronikhi esiyisisekelo seizigaba ze-quantum, ukuguqulwa kwesigaba se-quantum kanye nenjabulo yezinto eziningi ezinganyakazi ezigabeni ze-quantum. Ezisetshenziswa ze-topological, ukuhlangana phakathi kwamazinga amaningi enkululeko, njengama-electron, amaphononi kanye ne-spin, kudlala indima ebalulekile ekuqondeni nasekulawuleni izakhiwo zezinto ezibonakalayo. Ukuvuswa okukhanyayo kungasetshenziswa ukuhlukanisa phakathi kokusebenzelana okuhlukile futhi kulawule isimo sendaba, futhi ulwazi mayelana nezakhiwo eziyisisekelo zezinto ezibonakalayo, ukuguqulwa kwesigaba sesakhiwo, nezimo ezintsha ze-quantum zingase zitholakale. Njengamanje, ubudlelwano phakathi kokuziphatha kwe-macroscopic yezinto ze-topological eziqhutshwa inkambu yokukhanya kanye nesakhiwo sazo se-athomu encane kanye nezakhiwo ze-elekthronikhi sekuyinhloso yocwaningo.
Indlela yokusabela yesithombe kagesi yezinto ze-topological ihlobene eduze nesakhiwo sayo se-elekthronikhi esincane. Ngama-semi-metals e-topological, injabulo yenkampani yenethiwekhi eduze nendawo yomgwaqo yebhendi izwela kakhulu kuzici zokusebenza kwegagasi zesistimu. Ucwaningo lwezenzakalo ze-optical nonlinear ku-semi-metals ye-topological lungasisiza ukuba siqonde kangcono izakhiwo ezingokomzimba zezifunda ezijabulile zohlelo, futhi kulindeleke ukuthi le miphumela ingasetshenziswa ekwenzeniimishini yokubonakanye nokuklanywa kwamaseli elanga, ahlinzeka ngezinhlelo zokusebenza ezingokoqobo esikhathini esizayo. Isibonelo, ku-semi-metal ye-Weyl, ukumunca i-photon yokukhanya okuyindilinga okumhlophe kuzobangela ukuthi i-spin ijike, futhi ukuze kuhlangatshezwane nokongiwa komfutho we-angular, isasasa le-electron ezinhlangothini zombili zekhoni ye-Weyl izosatshalaliswa ngokulinganayo isiqondiso sokusakazwa kokukhanya kwe-circularly polarized, okubizwa ngokuthi umthetho wokukhethwa kwe-chiral (Umfanekiso 1).
Ucwaningo lwetiyori lwezenzakalo ze-optical nonlinear ze-topological material ngokuvamile lwamukela indlela yokuhlanganisa ukubalwa kwezakhiwo zezwe elibalulekile kanye nokuhlaziywa kwe-symmetry. Nokho, le ndlela inokukhubazeka okuthile: ayinalo ulwazi lwesikhathi sangempela olushukumisayo lwabathwali abajabulile esikhaleni somfutho kanye nesikhala sangempela, futhi ayikwazi ukusungula ukuqhathanisa okuqondile nendlela yokuhlola exazululwe isikhathi. Ukuhlangana phakathi kwamaphononi ama-electron namaphononi akunakwa. Futhi lokhu kubalulekile ukuze kwenzeke izinguquko ezithile zesigaba. Ngaphezu kwalokho, lokhu kuhlaziywa kwethiyori okusekelwe kumbono wokuphazamisa akukwazi ukubhekana nezinqubo zomzimba ngaphansi kwenkambu yokukhanya eqinile. Ukulingisa okuncike esikhathini okuncike ku- density functional molecular dynamics (TDDFT-MD) okusekelwe ezimisweni zokuqala kungaxazulula izinkinga ezingenhla.
Muva nje, ngaphansi kokuqondisa komcwaningi uMeng Sheng, umcwaningi we-postdoctoral u-Guan Mengxue kanye nomfundi ofundela ubudokotela u-Wang En we-SF10 Group of the State Key Laboratory of Surface Physics of the Institute of Physics of the Chinese Academy of Sciences/Beijing National Research Center for Concentrated Matter. I-Physics, ngokubambisana noSolwazi u-Sun Jiatao we-Beijing Institute of Technology, basebenzise isofthiwe yokulingisa ye-TDAP yesimo esijabulisayo esizithuthukisile. Izici zokuphendula ze-quastiparticle excitation ku-ultrafast laser ohlotsheni lwesibili lwe-Weyl semi-metal WTe2 ziyaphenywa.
Kubonisiwe ukuthi isasasa elikhethiwe labathwali eduze nephoyinti le-Weyl linqunywa i-atomic orbital symmetry kanye nomthetho wokukhetha inguquko, ohlukile kumthetho ojwayelekile wokukhethwa kwe-spin we-chiral excitation, futhi indlela yawo yokuvusa ingalawulwa ngokushintsha isiqondiso se-polarization. wokukhanya kwe-polarized linearly namandla e-photon (FIG. 2).
I-asymmetric excitation yezinkampani zenethiwekhi ingenisa ama-photocurrents ezindaweni ezihlukene endaweni yangempela, okuthinta isiqondiso nokulinganisa kokushelela kwe-interlayer yesistimu. Njengoba izakhiwo ze-topological ze-WTe2, njengenani lamaphoyinti e-Weyl kanye nezinga lokuhlukaniswa endaweni yomfutho, kuncike kakhulu ekulinganisweni kwesistimu (Umfanekiso 3), ukuthakazelisa kwe-asymmetric yabathwali kuzoletha ukuziphatha okuhlukile kwe-Weyl. ama-quastiparticles esikhaleni somfutho kanye nezinguquko ezihambisanayo ezakhiweni ze-topological zesistimu. Ngakho-ke, ucwaningo lunikeza umdwebo wesigaba esicacile sokuguqulwa kwesigaba se-phototopological (Umfanekiso 4).
Imiphumela ibonisa ukuthi i-chirality ye-excitation yenkampani yenethiwekhi kufanele inakwe, futhi izici ze-athomu ze-orbital yokusebenza kwegagasi kufanele zihlaziywe. Imiphumela yakho kokubili iyafana kodwa indlela ngokusobala yehlukile, enikeza isisekelo setiyetha sokuchaza ubunye bamaphuzu e-Weyl. Ngaphezu kwalokho, indlela yokubala eyamukelwe kulolu cwaningo ingaqonda ngokujulile ukusebenzisana okuyinkimbinkimbi kanye nokuziphatha okuguquguqukayo emazingeni e-athomu ne-elekthronikhi ngesilinganiso sesikhathi esishesha kakhulu, iveze izindlela zabo ze-microphysical, futhi kulindeleke ukuthi ibe yithuluzi elinamandla locwaningo lwangomuso mayelana. izenzakalo ze-optical nonlinear ezintweni ze-topological.
Imiphumela ikuphephabhuku iNature Communications. Umsebenzi wocwaningo usekelwa Uhlelo Lukazwelonke Lokucwaninga Nokuthuthukiswa Okubalulekile, I-National Natural Science Foundation kanye ne-Strategic Pilot Project (Isigaba B) se-Chinese Academy of Sciences.
I-FIG.1.a. Umthetho wokukhetha ubucwebe bamaphuzu e-Weyl anophawu oluhle (χ=+1) ngaphansi kokukhanya okuyisiyingi; Injabulo ekhethiwe ngenxa yokulinganisa kwe-athomu ye-orbital endaweni ye-Weyl ka-b. χ=+1 ekukhanyeni kwe-polarized ku-inthanethi
I-FIG. 2. Umdwebo wesakhiwo se-athomu sika-a, Td-WTe2; b. Isakhiwo sebhendi eduze kwendawo yeFermi; (c) Isakhiwo sebhendi neminikelo ehlobene yama-athomu ajikelezayo asatshalaliswa emigqeni yokulinganisa ephezulu esifundeni sase-Brillouin, imicibisholo (1) kanye (2) imele injabulo eseduze noma ekude namaphoyinti e-Weyl, ngokulandelanayo; d. Ukukhulisa ukwakheka kwebhendi ngakundlela ye-Gamma-X
I-FIG.3.ab: Ukunyakaza kwe-interlayer okuhlobene kwesiqondisindlela se-polarized light polarization eduze kwe-A-eksisi ne-B-eksisi yekristalu, kanye nemodi yokunyakaza ehambisanayo iyaboniswa; C. Ukuqhathanisa phakathi kokulingisa kwetiyetha nokubhekwa kokuhlola; de: I-Symmetry evolution yesistimu nendawo, inombolo kanye nezinga lokuhlukaniswa kwamaphoyinti e-Weyl aseduze kakhulu endizeni ye-kz=0
I-FIG. 4. Inguquko yesigaba se-Phototopological ku-Td-WTe2 yamandla e-photon okukhanya ahlukanisiwe (?) ω) nesiqondisindlela se-polarization (θ) umdwebo wesigaba esincike
Isikhathi sokuthumela: Sep-25-2023