Inkqubela yenziwe kwisifundo sokunyakaza kwe-ultrafast ye-Weil quasiparticles elawulwa yiiilaser
Kwiminyaka yakutshanje, uphando lwethiyori kunye novavanyo malunga ne-topological quantum states kunye ne-topological quantum materials ibe ngumxholo oshushu kwicandelo le-condensed matter physics.Njengombono omtsha wokuhlelwa kwezinto, ulandelelwano lwe-topological, njenge-symmetry, ngumbono osisiseko kwi-condensed matter physics.Ukuqonda okunzulu kwe-topology kunxulumene neengxaki ezisisiseko kwi-condensed matter physics, njengesiseko se-electronic structureizigaba zequantum, ukutshintshwa kwesigaba se-quantum kunye nokukhuthazwa kwezinto ezininzi ezingenakunyakaziswa kwizigaba ze-quantum.Kwimathiriyeli ye-topological, ukudibanisa phakathi kwamanqanaba amaninzi enkululeko, njengee-electron, iiphononi kunye ne-spin, idlala indima ebalulekileyo ekuqondeni nasekulawuleni iimpawu eziphathekayo.Uvuselelo olukhanyayo lunokusetyenziswa ukwahlula phakathi konxibelelwano olwahlukeneyo kunye nokukhohlisa imeko yento, kunye nolwazi malunga neempawu ezisisiseko zemathiriyeli, utshintsho lwenqanaba lolwakhiwo, kunye namazwe amatsha e-quantum inokufumaneka.Okwangoku, ubudlelwane phakathi kokuziphatha kwe-macroscopic yezinto ze-topological eziqhutywa yintsimi yokukhanya kunye ne-microscopic ye-athomu ye-athomu kunye neempawu ze-elektroniki ziye zaba yinjongo yophando.
Ukuziphatha kwempendulo yefoto yombane wezinto ze-topological inxulumene ngokusondeleyo nesakhiwo sayo sombane esincinci.Kwii-semi-metals ze-topological, i-excitation ye-carrier carrier kufuphi ne-band intersection inovakalelo oluphezulu kwiimpawu zomsebenzi wamaza wenkqubo.Uphononongo lweziganeko ze-optical nonlinear kwi-topological semi-metals lunokusinceda ukuba siqonde ngcono iipropathi ezibonakalayo zamazwe achulumancisayo enkqubo, kwaye kulindeleke ukuba ezi ziphumo zingasetyenziswa ekwenzeniizixhobo zamehlokunye nokuyila iiseli zelanga, ukubonelela ngokusetyenziswa okusebenzayo kwixesha elizayo.Umzekelo, kwi-semi-metal ye-Weyl, ukufunxa ifoton yokukhanya okujikelezayo okujikelezayo kuya kubangela ukuba i-spin ijike, kwaye ukuze kuhlangatyezwane nogcino lwesantya se-angular, i-electron excitation kumacala omabini e-Weyl cone iya kusasazwa ngokulinganayo. ulwalathiso lwe-circularly polarized light propagation, ebizwa ngokuba ngumgaqo wokukhethwa kwe-chiral (Umfanekiso 1).
Uphononongo lwethiyori yeziganeko ze-optical nonlinear ze-topological materials ngokuqhelekileyo zithatha indlela yokudibanisa ukubalwa kwezinto eziphathekayo zomhlaba kunye nohlalutyo lwe-symmetry.Nangona kunjalo, le ndlela ineziphene ezithile: ayinalo ulwazi lwexesha lokwenyani oluguquguqukayo lwabathwali abanomdla kwisithuba sokukhawuleza kunye nendawo yangempela, kwaye ayikwazi ukuseka uthelekiso oluthe ngqo kunye nendlela yokukhangela umfuniselo wexesha.Ukudibanisa phakathi kwee-electron-phonon kunye ne-photon-phonon ayikwazi ukuqwalaselwa.Kwaye oku kubalulekile kwiinguqu ezithile zesigaba ukuba zenzeke.Ukongezelela, olu hlalutyo lwethiyori olusekelwe kwi-theory ye-perturbation alukwazi ukujongana neenkqubo zomzimba phantsi kwendawo yokukhanya eqinile.Ixesha elixhomekeke kwi-density functional dynamics dynamics (TDDFT-MD) esekelwe kwimigaqo yokuqala inokusombulula ezi ngxaki zingentla.
Kutshanje, phantsi kwesikhokelo somphandi uMeng Sheng, umphandi wangemva kogqirha uGuan Mengxue kunye nomfundi ogqirha uWang En weSF10 Iqela leLabhoratri yeState Key yeFiziksi yoMda weZiko leFiziksi yeZiko laseTshayina lezeSayensi / iZiko loPhando leSizwe laseBeijing loMba oNxibeleleyo. I-Physics, ngokubambisana noNjingalwazi u-Sun Jiatao we-Beijing Institute of Technology, basebenzise i-software ye-TDAP ephuhlisweyo echulumancisayo.Iimpawu zokuphendula ze-quastiparticle excitation kwi-ultrafast laser kudidi lwesibini lwe-Weyl semi-metal WTe2 ziyaphandwa.
Kuye kwaboniswa ukuba ukutshatyalaliswa okukhethiweyo kwabathwali kufuphi nendawo ye-Weyl kuchongwa yi-atomic orbital symmetry kunye nomgaqo wokukhethwa kwenguqu, eyahlukileyo kumgaqo oqhelekileyo wokukhetha i-spin ye-chiral excitation, kwaye indlela yayo yokuvuselela inokulawulwa ngokuguqula isalathiso se-polarization. yokukhanya komgca we-polarized kunye namandla e-photon (FIG. 2).
I-excitation ye-asymmetric ye-carriers ibangela i-photocurrents kwiindlela ezahlukeneyo kwindawo yangempela, echaphazela ulwalathiso kunye ne-symmetry ye-interlayer slip yenkqubo.Ekubeni iipropati ze-topological ze-WTe2, ezifana nenani lamanqaku e-Weyl kunye neqondo lokuhlukana kwisithuba sokukhawuleza, zixhomekeke kakhulu kwi-symmetry yenkqubo (Umfanekiso we-3), i-excitation ye-asymmetric yabathwali iya kuzisa ukuziphatha okwahlukileyo kwe-Weyl. i-quastiparticles kwisithuba somfutho kunye neenguqu ezihambelanayo kwiipropati ze-topological zenkqubo.Ngaloo ndlela, isifundo sibonelela ngomzobo wesigaba esicacileyo sokutshintshwa kwesigaba se-phototopological (Umfanekiso 4).
Iziphumo zibonisa ukuba i-chirality ye-excitation ye-carrier kufuphi ne-Weyl point kufuneka inikwe ingqwalasela, kunye neempawu ze-athom ze-orbital yomsebenzi wamaza kufuneka zihlalutywe.Iziphumo zezi zimbini ziyafana kodwa indlela yokusebenza yahlukile, ebonelela ngesiseko sethiyori sokucacisa ubunye bamanqaku e-Weyl.Ukongeza, indlela yokubala eyamkelwe kolu phononongo inokuqonda ngokunzulu intsebenziswano entsonkothileyo kunye nokuziphatha okuguquguqukayo kumanqanaba e-athomu kunye ne-elektroniki kwinqanaba elikhawulezayo lexesha, iveze iindlela zabo ze-microphysical, kwaye kulindeleke ukuba ibe sisixhobo esinamandla sophando lwexesha elizayo. i-nonlinear optical phenomena kwizinto ze-topological.
Iziphumo zikwijenali yoNxibelelwano lweNdalo.Umsebenzi wophando uxhaswa yiSicwangciso soPhando oluPhambili oluPhambili kunye noPhuhliso lweSizwe, iSiseko seSizwe seSayensi yeNdalo kunye neProjekthi yeSicwangciso soLingo (iCandelo B) leZiko leeSayensi zaseTshayina.
UMFANEKISO1.a.Umgaqo wokukhetha i-chirality yeengongoma ze-Weyl ezinophawu oluhle lwe-chirality (χ=+1) phantsi kokukhanya okujikelezayo okujikelezayo;Uvuselelo olukhethiweyo ngenxa ye-atomic orbital symmetry kwindawo ye-Weyl ye-b.χ=+1 kwisikhanyiso se-polarized kwi-intanethi
IKHIWANE.2. Umzobo wesakhiwo seathom ye-a, Td-WTe2;b.Isakhiwo sebhendi kufuphi nomphezulu weFermi;(c) Ulwakhiwo lwebhendi kunye negalelo elizalanayo lee-athom orbitals ezisasazwe ngemigca yeesimmetrikhi eziphezulu kwingingqi yaseBrillouin, iintolo (1) kunye (2) zibonisa uchulumanco kufutshane okanye kude kwiindawo ze-Weyl, ngokulandelelanayo;d.Ukwandiswa kwesakhiwo sebhendi ecaleni kwendlela yeGamma-X
I-FIG.3.ab: Intshukumo ehambelanayo ye-interlayer ye-linearly polarized light polarization direction ecaleni kwe-A-axis kunye ne-B-axis ye-crystal, kunye nemowudi yokunyakaza ehambelanayo ibonakalisiwe;C. Ukuthelekisa phakathi kokulinganisa kwethiyori kunye nokuqwalaselwa kovavanyo;de: I-Symmetry evolution yesixokelelwano kunye nendawo, inani kunye neqondo lokwahlulwa kweendawo ezimbini ze-Weyl ezikufutshane kwinqwelomoya ye-kz=0
IKHIWANE.4. Utshintsho lwesigaba sePhototopological kwi-Td-WTe2 yokukhanya okukhanyayo okukhanyayo (?) ω) kunye nesalathiso se-polarization (θ) kwidayagram yesigaba esixhomekeke kwidayagram
Ixesha lokuposa: Sep-25-2023