Kufambira mberi kwakaitwa mukudzidza kwekufamba nekukurumidza kweWeil quasiparticles inodzorwa nelaser

Kufambira mberi kwakaitwa mukudzidza kwekufamba nekukurumidza kweWeil quasiparticles inodzorwa nelasers

Mumakore achangopfuura, tsvakiridzo yedzidziso uye yekuyedza pamusoro pemamiriro e topological quantum uye zvinhu zve topological quantum yave nyaya inonyanya kutaurwa munyaya ye combined matter physics. Sepfungwa itsva yekupatsanura zvinhu, topological order, se symmetry, ipfungwa huru mu condensed matter physics. Kunzwisisa kwakadzama kwe topology kwakabatana nematambudziko makuru mu condensed matter physics, akadai se basic electronic structure yezvikamu zve quantum, kushanduka kwechikamu chequantum uye kukwidziridzwa kwezvinhu zvakawanda zvisingafambi muzvikamu zvequantum. Muzvinhu zvetopological, kubatana pakati pemadhigirii mazhinji erusununguko, akadai semaerekitironi, maphononi uye kutenderera, kunoita basa guru mukunzwisisa nekugadzirisa hunhu hwezvinhu. Kukwidziridzwa kwechiedza kunogona kushandiswa kusiyanisa pakati pekudyidzana kwakasiyana uye kushandura mamiriro ezvinhu, uye ruzivo nezvehunhu hwepakutanga hwezvinhu, kushanduka kwechikamu chechimiro, uye mamiriro matsva equantum zvinogona kuwanikwa. Parizvino, hukama huripo pakati pehunhu hwemacroscopic hwezvinhu zvetopological zvinotungamirirwa nechiedza uye chimiro chazvo chemaatomu emicroscopic uye hunhu hwemagetsi hwave chinangwa chekutsvagisa.

Maitiro e photoelectric response ezvinhu zve topological anoenderana zvakanyanya ne microscopic electronic structure yayo. Kune topological semi-metals, carrier excitation iri pedyo ne band intersection inonyanya kuenderana nemaitiro e wave function e system. Kudzidza nezve nonlinear optical phenomena mu topological semi-metals kunogona kutibatsira kunzwisisa zviri nani hunhu hwemuviri hwe excited states dze system, uye zvinotarisirwa kuti mhedzisiro iyi inogona kushandiswa mukugadzirazvishandiso zvemazisouye dhizaini yemasero ezuva, zvichipa mukana wekushandisa mune ramangwana. Semuenzaniso, muWeyl semi-metal, kutora photon yechiedza chakatenderera chinotenderedzwa kuchaita kuti kutenderera kutenderere, uye kuitira kuchengetedza angular momentum, electron excitation kumativi ese eWeyl cone ichagoverwa zvisina kuenzana munzira yekupararira kwechiedza chakatenderera chinotenderedzwa, chinonzi chiral selection rule (Mufananidzo 1).

Chidzidzo chedzidziso chezviitiko zvisina kujeka zvezvinhu zve topological chinowanzo tora nzira yekubatanidza kuverenga kwemamiriro ezvinhu epasi uye kuenzanisa. Zvisinei, nzira iyi ine zvimwe zvikanganiso: haina ruzivo rwechokwadi rwenguva yekuchinja kwevatakuri vane mufaro munzvimbo ye momentum nenzvimbo chaiyo, uye haigone kuumba kuenzanisa kwakananga nenzira yekuedza yekuona yakagadziriswa nenguva. Kubatana pakati pema electron-phonons nema photon-phonons hakugone kufungwa. Uye izvi zvakakosha kuti dzimwe shanduko dzechikamu dziitike. Pamusoro pezvo, iyi ongororo yedzidziso yakavakirwa padzidziso ye perturbation haigone kubata nemaitiro epanyama pasi pesimba rechiedza. Kutevedzera kwe time-dependent density functional molecular dynamics (TDDFT-MD) kwakavakirwa pamisimboti yekutanga kunogona kugadzirisa matambudziko ari pamusoro apa.

Munguva pfupi yapfuura, vachitungamirirwa nemuongorori Meng Sheng, muongorori we postdoctoral Guan Mengxue nemudzidzi wedoctorate Wang En weSF10 Group yeState Key Laboratory yeSurface Physics yeInstitute of Physics yeChinese Academy of Sciences/Beijing National Research Center for Concentrated Matter Physics, vachishanda pamwe chete naProfessor Sun Jiatao weBeijing Institute of Technology, vakashandisa software yekuzvigadzira excited state dynamics simulation TDAP. Hunhu hwemhinduro yequastiparticle excitation kune ultrafast laser mumhando yechipiri yeWeyl semi-metal WTe2 hunoongororwa.

Zvakaratidzwa kuti kusarudzwa kwekufambiswa kwezvinotakura zviri pedyo neWeyl point kunotsanangurwa neatomic orbital symmetry uye transition selection rule, iyo yakasiyana nemutemo wenguva dzose wekusarudza spin wekuwedzera kwechiral, uye nzira yayo yekufambiswa inogona kudzorwa nekushandura nzira yekuparara kwechiedza chine polarized linearly uye photon energy (Mufananidzo 2).

Kusawirirana kwevatakuri kunokonzera ma photocurrents munzira dzakasiyana munzvimbo chaiyo, izvo zvinokanganisa kutungamira uye kuenzana kwekutsvedza kwepakati pehurongwa. Sezvo hunhu hweWTe2, hwakadai sehuwandu hweWeyl points uye mwero wekuparadzaniswa munzvimbo ye momentum, zvichitsamira zvakanyanya pakuenzana kwehurongwa (Mufananidzo 3), kusawirirana kwevatakuri kuchaunza maitiro akasiyana eWeyl quastiparticles munzvimbo ye momentum uye shanduko dzinoenderana muhunhu hwe topological hwehurongwa. Saka, chidzidzo ichi chinopa dhayagiramu yakajeka yekuchinja kwe phototopological phase (Mufananidzo 4).

Zvakawanikwa zvinoratidza kuti chirality ye carrier excitation iri pedyo neWeyl point inofanira kutariswa, uye hunhu hweatomic orbital hwe wave function hunofanira kuongororwa. Mhedzisiro yezviri zviviri zvakafanana asi mashandiro acho akasiyana zviri pachena, izvo zvinopa hwaro hwedzidziso yekutsanangura hunhu hweWeyl points. Pamusoro pezvo, nzira yekuverenga yakashandiswa muchidzidzo ichi inogona kunzwisisa zvakadzama kudyidzana kwakaoma uye maitiro e dynamical pamazinga eatomu neemagetsi munguva inokurumidza, kuratidza mashandiro avo e microphysical, uye inotarisirwa kuva chishandiso chine simba chekutsvagisa mune ramangwana pane nonlinear optical phenomena muzvinhu zve topological.

Mhedzisiro yacho iri mumagazini yeNature Communications. Basa rekutsvagisa iri rinotsigirwa neNational Key Research and Development Plan, National Natural Science Foundation pamwe neStrategic Pilot Project (Category B) yeChinese Academy of Sciences.

Mufananidzo 1.a. Mutemo wekusarudza chirality yemapoinzi eWeyl ane chiratidzo chechirality chakanaka (χ=+1) pasi pechiedza chakatenderera; Kufara kwekusarudza nekuda kweatomic orbital symmetry panzvimbo yeWeyl ye b. χ=+1 muchiedza chakapararira chepamhepo.

Mufananidzo 2. Dhayagiramu yechimiro cheAtomu chea, Td-WTe2; b. Chimiro chebhendi pedyo neFermi surface; (c) Chimiro chebhendi uye mipiro yeatomu orbital yakagoverwa pamwe chete nemitsetse yakaenzana munzvimbo yeBrillouin, miseve (1) uye (2) inomiririra kufadza pedyo kana kure neWeyl points, zvichiteerana; d. Kuwedzera kwechimiro chebhendi pamwe chete negwara reGamma-X

Mufananidzo 3.ab: Kufamba kwepakati pezvikamu zvemwenje wepolarized light linearly polarized pamwe chete neA-axis neB-axis yekristaro, uye movement mode inoenderana nayo inoratidzwa; C. Kuenzanisa pakati pekufananidzira kwedzidziso uye kuongororwa kwekuyedza; de: Symmetry evolution yesystem nenzvimbo, nhamba uye dhigirii rekuparadzaniswa kwemapoinzi maviri eWeyl ari pedyo mu kz=0 plane

Mufananidzo 4. Kuchinja kwechikamu chephototopological muTd-WTe2 yesimba rephoton rechiedza chakapatsanurwa (?) ω) uye dhayagiramu yechikamu chinotsamira padivi (θ)