Kev kawm txog kev txav mus los sai ntawm Weil quasiparticles uas tswj los ntawmcov lasers
Nyob rau hauv xyoo tas los no, kev tshawb fawb theoretical thiab experimental ntawm topological quantum xeev thiab topological quantum cov ntaub ntawv tau dhau los ua ib qho tseem ceeb hauv kev tshawb fawb txog condensed matter physics. Raws li lub tswv yim tshiab ntawm kev faib tawm cov khoom, topological order, zoo li symmetry, yog lub tswv yim tseem ceeb hauv condensed matter physics. Kev nkag siab tob txog topology yog cuam tshuam nrog cov teeb meem yooj yim hauv condensed matter physics, xws li cov qauv hluav taws xob yooj yim ntawmtheem quantum, kev hloov pauv theem quantum thiab kev txhawb nqa ntawm ntau yam khoom tsis txav chaw hauv theem quantum. Hauv cov ntaub ntawv topological, kev sib txuas ntawm ntau qib kev ywj pheej, xws li electrons, phonons thiab spin, ua lub luag haujlwm txiav txim siab hauv kev nkag siab thiab tswj cov khoom siv. Kev txhawb nqa lub teeb tuaj yeem siv los sib txawv ntawm kev sib cuam tshuam sib txawv thiab tswj hwm lub xeev ntawm cov khoom, thiab cov ntaub ntawv hais txog cov khoom siv lub cev yooj yim, kev hloov pauv theem, thiab cov xeev quantum tshiab tuaj yeem tau txais. Tam sim no, kev sib raug zoo ntawm kev coj cwj pwm macroscopic ntawm cov ntaub ntawv topological tsav los ntawm lub teeb teb thiab lawv cov qauv atomic microscopic thiab cov khoom siv hluav taws xob tau dhau los ua lub hom phiaj tshawb fawb.
Tus cwj pwm teb photoelectric ntawm cov ntaub ntawv topological muaj feem cuam tshuam nrog nws cov qauv hluav taws xob me me. Rau cov hlau topological semi-metals, qhov kev txhawb nqa ntawm tus neeg nqa khoom ze ntawm qhov kev sib tshuam band yog qhov rhiab heev rau cov yam ntxwv ntawm nthwv dej ntawm lub kaw lus. Kev kawm txog cov xwm txheej optical nonlinear hauv topological semi-metals tuaj yeem pab peb nkag siab zoo dua txog cov khoom siv lub cev ntawm cov xeev zoo siab ntawm lub kaw lus, thiab nws xav tias cov teebmeem no tuaj yeem siv rau hauv kev tsim khoom ntawmcov khoom siv kho qhov muagthiab kev tsim cov hlwb hnub ci, muab cov kev siv tau zoo yav tom ntej. Piv txwv li, hauv Weyl semi-metal, kev nqus ib lub photon ntawm lub teeb ci ntsa iab yuav ua rau lub kiv tig, thiab txhawm rau kom ua tau raws li kev txuag ntawm lub zog angular, qhov kev txhawb nqa electron ntawm ob sab ntawm Weyl cone yuav raug faib tsis sib xws raws li kev taw qhia ntawm lub teeb ci ntsa iab, uas hu ua txoj cai xaiv chiral (Daim Duab 1).
Kev kawm txog cov xwm txheej tsis pom kev ntawm cov khoom siv topological feem ntau siv txoj kev sib xyaw ua ke ntawm kev suav cov khoom siv hauv av thiab kev tsom xam symmetry. Txawm li cas los xij, txoj kev no muaj qee qhov tsis zoo: nws tsis muaj cov ntaub ntawv dynamic tiag tiag ntawm cov neeg nqa khoom zoo siab hauv qhov chaw momentum thiab qhov chaw tiag tiag, thiab nws tsis tuaj yeem tsim kev sib piv ncaj qha nrog txoj kev tshawb nrhiav kev sim sijhawm. Kev sib txuas ntawm electron-phonons thiab photon-phonons tsis tuaj yeem xav txog. Thiab qhov no yog qhov tseem ceeb rau qee qhov kev hloov pauv theem kom tshwm sim. Tsis tas li ntawd, qhov kev tsom xam theoretical no raws li perturbation theory tsis tuaj yeem cuam tshuam nrog cov txheej txheem lub cev nyob rau hauv lub teeb muaj zog. Lub sijhawm-nyob ntawm qhov ceev functional molecular dynamics (TDDFT-MD) simulation raws li thawj cov ntsiab cai tuaj yeem daws cov teeb meem saum toj no.
Tsis ntev los no, nyob rau hauv kev coj ntawm tus kws tshawb fawb Meng Sheng, tus kws tshawb fawb postdoctoral Guan Mengxue thiab tus tub ntxhais kawm doctoral Wang En ntawm SF10 Group ntawm State Key Laboratory of Surface Physics ntawm lub koom haum ntawm Physics ntawm Suav Academy of Sciences / Beijing National Research Center for Concentrated Matter Physics, ua ke nrog Xibfwb Sun Jiatao ntawm Beijing Institute of Technology, lawv tau siv tus kheej tsim excited state dynamics simulation software TDAP. Cov yam ntxwv teb ntawm quastiparticle excitation rau ultrafast laser hauv hom thib ob ntawm Weyl semi-metal WTe2 raug tshawb xyuas.
Nws tau pom tias qhov kev xaiv tsa ntawm cov neeg nqa khoom ze ntawm Weyl point yog txiav txim siab los ntawm atomic orbital symmetry thiab kev xaiv hloov pauv txoj cai, uas txawv ntawm txoj cai xaiv tig rau chiral excitation, thiab nws txoj kev txhawb nqa tuaj yeem tswj tau los ntawm kev hloov pauv qhov kev taw qhia polarization ntawm lub teeb linearly polarized thiab photon zog (DAIM DUAB 2).
Qhov kev txhawb nqa asymmetric ntawm cov neeg nqa khoom ua rau cov photocurrents nyob rau hauv ntau qhov kev taw qhia hauv qhov chaw tiag tiag, uas cuam tshuam rau qhov kev taw qhia thiab kev sib npaug ntawm qhov sib txawv ntawm cov txheej txheem ntawm lub kaw lus. Txij li thaum cov khoom topological ntawm WTe2, xws li tus lej ntawm Weyl cov ntsiab lus thiab qib ntawm kev sib cais hauv qhov chaw momentum, yog nyob ntawm qhov sib npaug ntawm lub kaw lus (Daim Duab 3), qhov kev txhawb nqa asymmetric ntawm cov neeg nqa khoom yuav coj tus cwj pwm sib txawv ntawm Weyl quastiparticles hauv qhov chaw momentum thiab kev hloov pauv sib xws hauv cov khoom topological ntawm lub kaw lus. Yog li, kev tshawb fawb muab daim duab theem meej rau kev hloov pauv theem phototopological (Daim Duab 4).
Cov txiaj ntsig qhia tau tias qhov chirality ntawm carrier excitation ze Weyl point yuav tsum tau them sai sai rau, thiab cov khoom atomic orbital ntawm nthwv dej ua haujlwm yuav tsum tau soj ntsuam. Cov teebmeem ntawm ob qho zoo sib xws tab sis lub tshuab yog qhov sib txawv, uas muab lub hauv paus theoretical rau kev piav qhia txog singularity ntawm Weyl cov ntsiab lus. Tsis tas li ntawd, txoj kev suav lej tau txais hauv txoj kev tshawb fawb no tuaj yeem nkag siab tob txog kev sib cuam tshuam nyuaj thiab kev coj cwj pwm dynamic ntawm cov theem atomic thiab electronic hauv lub sijhawm ceev ceev, qhia lawv cov txheej txheem microphysical, thiab xav tias yuav yog lub cuab yeej muaj zog rau kev tshawb fawb yav tom ntej ntawm cov xwm txheej optical nonlinear hauv cov ntaub ntawv topological.
Cov txiaj ntsig tau muab tso rau hauv phau ntawv xov xwm Nature Communications. Cov haujlwm tshawb fawb tau txais kev txhawb nqa los ntawm National Key Research and Development Plan, National Natural Science Foundation thiab Strategic Pilot Project (Qeb B) ntawm Chinese Academy of Sciences.
DUAB 1.a. Txoj cai xaiv chirality rau Weyl cov ntsiab lus nrog cov cim chirality zoo (χ = + 1) nyob rau hauv lub teeb ci ntsa iab; Kev xaiv excitation vim yog atomic orbital symmetry ntawm Weyl point ntawm b. χ = + 1 nyob rau hauv lub teeb ci ntsa iab online
DUAB 2. Daim duab qhia txog cov qauv atomic ntawm a, Td-WTe2; b. Cov qauv band ze ntawm Fermi nto; (c) Cov qauv band thiab cov kev koom tes ntawm cov atomic orbitals faib raws cov kab symmetric siab hauv thaj tsam Brillouin, cov xub (1) thiab (2) sawv cev rau kev txhawb siab ze lossis deb ntawm Weyl cov ntsiab lus, raws li; d. Kev nthuav dav ntawm cov qauv band raws Gamma-X kev taw qhia
DUAB 3.ab: Kev txav mus los ntawm cov txheej txheem sib piv ntawm kev coj ua polarization ntawm lub teeb linearly polarized raws A-axis thiab B-axis ntawm lub siv lead ua, thiab hom kev txav mus los sib xws tau piav qhia; C. Kev sib piv ntawm kev sim ua theoretical thiab kev soj ntsuam simulation; de: Kev hloov pauv ntawm lub cev thiab qhov chaw, tus lej thiab qib ntawm kev sib cais ntawm ob lub ntsiab lus Weyl ze tshaj plaws hauv lub dav hlau kz = 0
DUAB 4. Kev hloov pauv theem phototopological hauv Td-WTe2 rau lub zog photon teeb linearly polarized (?) ω) thiab polarization direction (θ) nyob ntawm daim duab theem.
Lub sijhawm tshaj tawm: Cuaj hlis-25-2023