Kuye kwenziwa inkqubela phambili ekufundeni ukuhamba ngokukhawuleza kwee-Weil quasiparticles ezilawulwa yiiileyiza
Kwiminyaka yakutshanje, uphando lwethiyori nolwezilingo malunga neemeko ze-quantum ze-topological kunye nezixhobo ze-quantum ze-topological luye lwaba ngumxholo oshushu kwicandelo le-physics yezinto ezidityanisiweyo. Njengengcamango entsha yokuhlelwa kwezinto, ulungelelwaniso lwe-topological, njengolungelelwaniso, yingcamango esisiseko kwi-physics yezinto ezidityanisiweyo. Ukuqonda okunzulu kwe-topology kunxulumene neengxaki ezisisiseko kwi-physics yezinto ezidityanisiweyo, njengesakhiwo se-elektroniki esisisisekoizigaba ze-quantum, utshintsho lwesigaba se-quantum kunye nokuvuselela izinto ezininzi ezingashukumiyo kwizigaba ze-quantum. Kwizinto ze-topological, ukudibanisa phakathi kwamanqanaba amaninzi enkululeko, njengee-electron, ii-phonon kunye ne-spin, kudlala indima ebalulekileyo ekuqondeni nasekulawuleni iimpawu zezinto. Ukuvuselela ukukhanya kungasetyenziselwa ukwahlula phakathi kokunxibelelana okwahlukileyo kunye nokulawula imeko yezinto, kwaye ulwazi malunga neempawu zomzimba ezisisiseko zezinto, utshintsho lwesigaba solwakhiwo, kunye neemeko ezintsha ze-quantum lunokufunyanwa. Okwangoku, ubudlelwane phakathi kokuziphatha kwe-macroscopic kwezinto ze-topological eziqhutywa yintsimi yokukhanya kunye nesakhiwo sazo se-athomu encinci kunye neempawu ze-elektroniki lube yinjongo yophando.
Indlela yokuphendula nge-photoelectric kwizixhobo ze-topological inxulumene ngokusondeleyo nesakhiwo sayo se-elektroniki esincinci. Kwi-topological semi-metals, i-carrier excitation kufutshane ne-band intersection inovelwano kakhulu kwiimpawu zomsebenzi wamaza zenkqubo. Uphononongo lweziganeko ze-optical ezingezizo ezi-linear kwi-topological semi-metals lunokusinceda siqonde ngcono iimpawu zomzimba zeemeko ezivuselelweyo zenkqubo, kwaye kulindeleke ukuba ezi ziphumo zingasetyenziswa ekwenziweni kweizixhobo ezibonakalayokunye noyilo lweeseli zelanga, nto leyo enika ukusetyenziswa okunokwenzeka kwixesha elizayo. Umzekelo, kwi-Weyl semi-metal, ukufunxa i-photon yokukhanya okujikelezileyo okujikelezileyo kuya kubangela ukuba ukujikeleza kutshintshe, kwaye ukuze kuhlangatyezwane nokugcinwa komongo we-angular, i-electron excitation kumacala omabini e-Weyl cone iya kusasazwa ngokungalinganiyo kwicala lokusasazwa kokukhanya okujikelezileyo okujikelezileyo, okubizwa ngokuba ngumthetho wokukhetha i-chiral (Umfanekiso 1).
Uphononongo lwethiyori lweziganeko ze-optical ezingezizo ezithe ngqo zezinto ze-topological ludla ngokusebenzisa indlela yokudibanisa ukubalwa kweempawu zemeko yomhlaba wezinto kunye nohlalutyo lokulingana. Nangona kunjalo, le ndlela ineziphene ezithile: ayinalo ulwazi oluguquguqukayo lwexesha langempela lwezithuthi ezivuselelweyo kwindawo ye-momentum kunye nendawo yokwenyani, kwaye ayinakuseka uthelekiso oluthe ngqo nendlela yokufumanisa uvavanyo exazululwe ngexesha. Ukudibana phakathi kwee-electron-phonon kunye nee-photon-phonon akunakucingelwa. Kwaye oku kubalulekile ukuba kwenzeke utshintsho oluthile lwesigaba. Ukongeza, olu hlalutyo lwethiyori olusekelwe kwithiyori ye-perturbation alunakujongana neenkqubo zomzimba phantsi kwentsimi yokukhanya enamandla. Ukulinganisa i-time-dependent density functional molecular dynamics (TDDFT-MD) ngokusekelwe kwimigaqo yokuqala kunokusombulula iingxaki ezingentla.
Kutshanje, phantsi kolwalathiso lomphandi uMeng Sheng, umphandi we-postdoctoral uGuan Mengxue kunye 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, besebenzisana noNjingalwazi uSun Jiatao we-Beijing Institute of Technology, basebenzise isoftware yokulinganisa i-excited state dynamics simulation TDAP. Iimpawu zokuphendula ze-quastiparticle excitation kwi-ultrafast laser kuhlobo lwesibini lwe-Weyl semi-metal WTe2 ziyaphandwa.
Kuye kwaboniswa ukuba ukunyusa okukhethwayo kwabathwali kufutshane nenqaku leWeyl kugqitywa ngumgaqo wokulinganisa i-atomic orbital kunye nomthetho wokukhetha utshintsho, owahlukileyo kumthetho wokukhetha oqhelekileyo we-spin wokunyusa i-chiral, kwaye indlela yayo yokunyusa ingalawulwa ngokutshintsha indlela ye-polarization yokukhanya okuphola ngokulinganayo kunye namandla e-photon (UMfanekiso 2).
Ukunyuswa okungalinganiyo kwabathwali kubangela i-photocurrents kwiindlela ezahlukeneyo kwindawo yokwenyani, nto leyo echaphazela indlela kunye nokulingana kokutyibilika kwe-interlayer yenkqubo. Ekubeni iipropati ze-topological ze-WTe2, ezifana nenani lamanqaku e-Weyl kunye nomlinganiselo wokwahlukana kwindawo ye-momentum, zixhomekeke kakhulu kukulingana kwenkqubo (Umfanekiso 3), ukunyuswa okungalinganiyo kwabathwali kuya kuzisa ukuziphatha okwahlukileyo kwe-Weyl quastiparticles kwindawo ye-momentum kunye notshintsho oluhambelanayo kwiipropati ze-topological zenkqubo. Ngoko ke, olu phononongo lubonelela ngomzobo wesigaba ocacileyo wotshintsho lwesigaba se-phototopological (Umfanekiso 4).
Iziphumo zibonisa ukuba i-chirality ye-carrier excitation kufutshane ne-Weyl point kufuneka iqwalaselwe, kwaye kufuneka kuhlalutywe iipropati ze-atomic orbital zomsebenzi wamaza. Iziphumo zezi zimbini ziyafana kodwa indlela yokusebenza yahlukile ngokucacileyo, nto leyo enika isiseko sethiyori sokuchaza ubunye bee-point zeWeyl. Ukongeza, indlela yokubala eyamkelweyo kolu phononongo inokuqonda ngokunzulu ukusebenzisana okuntsonkothileyo kunye nokuziphatha okuguquguqukayo kumanqanaba e-athomu kunye ne-elektroniki kwisikali sexesha esikhawulezayo, ityhile iindlela zazo ze-microphysical, kwaye kulindeleke ukuba ibe sisixhobo esinamandla sophando lwexesha elizayo malunga neziganeko ze-optical ezingezizo ezingqalileyo kwizinto ze-topological.
Iziphumo zikwiphephabhuku iNature Communications. Umsebenzi wophando uxhaswa yiNational Key Research and Development Plan, iNational Natural Science Foundation kunye neStrategic Pilot Project (uDidi B) yeChinese Academy of Sciences.
UMZOBO 1.a. Umthetho wokukhetha i-chirality kwii-Weyl points ezine-positive chirality sign (χ=+1) phantsi kokukhanya okujikelezileyo okujikelezileyo; Uvuselelo olukhethiweyo ngenxa yokulingana kwe-atomic orbital kwindawo ye-Weyl ka-b. χ=+1 ekukhanyeni okujikelezileyo okukwi-intanethi
UMZOBO 2. Umzobo wesakhiwo se-atomic se-a, Td-WTe2; b. Ulwakhiwo lwebhendi kufutshane nomphezulu weFermi; (c) Ulwakhiwo lwebhendi kunye negalelo elihambelanayo lee-orbital ze-atomic ezisasazwe kwimigca ephezulu yokulinganisa kummandla weBrillouin, iintolo (1) kunye (2) zimele uvuyo olukufutshane okanye olukude namanqaku eWeyl, ngokulandelelana; d. Ukwandiswa kwesakhiwo sebhendi kwicala leGamma-X
UMZOBO 3.ab: Intshukumo ehambelanayo yecala le-polarization yokukhanya oku-linearly polarized kwi-A-axis kunye ne-B-axis yekristale, kunye nemo yokuhamba ehambelanayo ibonisiwe; C. Uthelekiso phakathi kokulinganisa okufundiswayo kunye nokuqwalaselwa kovavanyo; de: Ukuguquka kolungelelwaniso lwenkqubo kunye nendawo, inani kunye nenqanaba lokwahlukana kwamanqaku amabini asondeleyo eWeyl kwi-kz=0 plane
UMZOBO 4. Utshintsho lwesigaba se-phototopological kwi-Td-WTe2 yamandla e-photon yokukhanya okuphola ngokwe-linearly polarized light (?) ω) kunye nomzobo wesigaba esixhomekeke kwi-polarization direction (θ)
Ixesha lokuthumela: Septemba-25-2023