Kufambira mberi kwakaitwa mukudzidza kweiyo ultrafast kufamba kweWeil quasiparticles inodzorwa nalasers
Mumakore achangopfuura, iyo theoretical uye yekuyedza tsvagiridzo yetopological quantum states uye topological quantum zvinhu yave musoro unopisa mumunda weyakapfupikiswa nyaya fizikisi.Sepfungwa nyowani yekuronga zvinhu, kurongeka kwetopological, sesymmetry, ipfungwa yakakosha mufizikisi yenyaya.Kunzwisisa kwakadzama kwetopology kune hukama nezvinetso zvekutanga mune yakapfupikiswa nyaya fizikisi, seyakakosha yemagetsi chimiro chequantum phases, quantum phase transition uye excitation yeakawanda immobilized elements mu quantum phases.Muzvinyorwa zvetopological, kubatanidza pakati pemadhigirii mazhinji erusununguko, senge maerekitironi, phononi uye spin, inoita basa rekunzwisisa mukunzwisisa uye kudzora zvinhu zvezvinhu.Kuwedzeredza kwechiedza kunogona kushandiswa kusiyanisa pakati pekudyidzana kwakasiyana uye kushandura mamiriro ezvinhu, uye ruzivo pamusoro pezvinhu zvakakosha zvemuviri zvimiro, shanduko yechikamu chekuchinja, uye hutsva hwehuwandu hunogona kuwanikwa.Parizvino, hukama pakati pemacroscopic maitiro ezvinyorwa zvetopological zvinofambiswa nechiedza chemunda uye yavo microscopic atomic chimiro uye zvemagetsi zvivakwa chave chinangwa chekutsvagisa.
Iyo photoelectric mhinduro maitiro e topological zvinhu zvine hukama neiyo microscopic yemagetsi chimiro.Kune topological semi-metals, iyo inotakura excitation padyo nebhendi mharadzano inonzwa zvakanyanya kune wave basa maitiro eiyo system.Kudzidza kweasina mutsara optical phenomena mune topological semi-metals kunogona kutibatsira kuti tinzwisise zviri nani zvinhu zvemuviri zvezvinofadza zvehurongwa, uye zvinotarisirwa kuti izvi zvinokonzeresa zvinogona kushandiswa mukugadziraoptical devicesuye dhizaini yemasero ezuva, achipa zvingangoshanda zvekushandisa mune ramangwana.Semuenzaniso, muWeyl semi-metal, kutora fotoni ye denderedzwa polarized mwenje kuchaita kuti kutenderera kutenderere, uye kuti isangane nekuchengetedzwa kweangular kasi, iyo electron excitation pamativi ese eWeyl cone ichagoverwa asymmetrically pamwe chete. kutungamira kwekupararira kwechiedza che circularly polarized, iyo inonzi chiral selection rule (Mufananidzo 1).
The theoretical study of nonlinear optical phenomena of topological materials kazhinji inotora nzira yekubatanidza kuverenga kwezvinhu zvepasi mamiriro ehupfumi uye symmetry analysis.Zvisinei, iyi nzira ine humwe hurema: inoshaya ruzivo rwechokwadi-nguva yevatakuri vanofara munzvimbo yekukurumidza uye nzvimbo chaiyo, uye haigoni kuisa kuenzanisa kwakananga neyakagadziriswa nzira yekuongorora yekuongorora.Kubatana pakati pe electron-phonons uye photon-phononi hakugoni kutariswa.Uye izvi zvakakosha kuti dzimwe nhanho shanduko dziitike.Mukuwedzera, iyi dzidziso yekuongorora inobva pakuvhiringidza dzidziso haigoni kutarisana nemaitiro emuviri pasi pechiedza chakasimba.Iyo nguva-inotsamira density functional molecular dynamics (TDDFT-MD) simulation yakavakirwa pamisimboti yekutanga inogona kugadzirisa matambudziko ari pamusoro.
Nguva pfupi yadarika, pasi pekutungamirwa nemuongorori Meng Sheng, postdoctoral muongorori Guan Mengxue uye mudzidzi wechiremba Wang En weSF10 Boka reState Key Laboratory yeSurface Physics yeInstitute of Physics yeChinese Academy yeSainzi/Beijing National Research Center for Concentrated Matter. Fizikisi, vachibatsirana naProfessor Sun Jiatao weBeijing Institute of Technology, vakashandisa iyo yakazvigadzira yakanakidzwa yenyika inosimudzira simulation software TDAP.Maitiro ekupindura maitiro e quastiparticle excitation kune Ultrafast laser mune yechipiri mhando yeWeyl semi-simbi WTe2 inoongororwa.
Zvave zvichiratidzwa kuti kusarudzwa kwekunakidzwa kwevatakuri pedyo neWeyl point kunotarirwa neatomic orbital symmetry uye shanduko yekusarudza mutemo, iyo yakasiyana neyakajairwa spin yekusarudza mutemo wechiral excitation, uye nzira yayo yekufadza inogona kudzorwa nekushandura nzira yepolarization. ye linearly polarized chiedza uye photon simba (FIG. 2).
The asymmetric excitation of carriers induces photocurrents in different directions in real space, iyo inokanganisa kutungamira uye symmetry ye interlayer slip yehurongwa.Sezvo iyo topological zvimiro zveWTe2, senge nhamba yeWeyl mapoinzi uye dhigirii rekuparadzaniswa munzvimbo yekukurumidza, inotsamira zvakanyanya pane symmetry yehurongwa (Mufananidzo 3), iyo asymmetric excitation yevatakuri ichaunza maitiro akasiyana eWeyl. quastiparticles munzvimbo yekukurumidza uye inowirirana shanduko mune yepamusoro-soro maitiro ehurongwa.Nokudaro, chidzidzo chinopa dhiyabhorosi yakajeka ye phototopological phase transitions (Mufananidzo 4).
Mhedzisiro yacho inoratidza kuti chirality yekunakidzwa kwemutakuri pedyo neWeyl point inofanirwa kutariswa, uye atomic orbital properties ye wave function inofanirwa kuongororwa.Mhedzisiro yezviviri izvi zvakafanana asi magadzirirwo ari pachena akasiyana, ayo anopa hwaro hwekufungidzira hwekutsanangura humwe hweWeyl mapoinzi.Pamusoro pezvo, iyo nzira yekombuta yakagamuchirwa muchidzidzo ichi inogona kunzwisisa zvakadzama kudyidzana kwakaomarara uye mafambiro ane simba paatomu uye zvemagetsi nhanho mune yepamusoro-yekukurumidza nguva chiyero, kuratidza maitiro avo emicrophysical, uye inotarisirwa kuve chishandiso chine simba chekutsvaga mune ramangwana pamusoro. nonlinear optical phenomena mune topological zvinhu.
Mhedzisiro yacho iri mujenari Nature Communications.Basa rekutsvaga rinotsigirwa neNational Key Research and Development Plan, National Natural Science Foundation uye Strategic Pilot Project (Chikamu B) cheChinese Academy of Sciences.
FIG.1.a.Mutemo wekusarudza chirality weWeyl points ine positive chirality sign (χ=+1) pasi pechiedza chakatenderera;Sarudzo yekunakidzwa nekuda kweatomic orbital symmetry paWeyl point ye b.χ=+1 mu-on-line polarized mwenje
FIG.2. Atomic chimiro dhayagiramu ye, Td-WTe2;b.Band chimiro pedyo neFermi pamusoro;(c) Chimiro chebhendi uye mipiro yakaenzana yeatomic orbitals yakagoverwa nemitsetse yakakwira inoenzanirana mudunhu reBrillouin, miseve (1) uye (2) inomiririra mafaro ari pedyo kana kure kubva kuWeyl points, zvichiteerana;d.Kukwidziridzwa kwebhendi chimiro padivi peGamma-X nzira
FIG.3.ab: Iyo inoenderana interlayer kufamba kweiyo linearly polarized light polarization direction pamwe neA-axis uye B-axis yekristaro, uye inoenderana mafambiro modhi inoratidzwa;C. Kuenzanisa pakati pezvinyorwa zvekufungidzira uye kuongorora kwekuedza;de: Symmetry shanduko yehurongwa uye chinzvimbo, nhamba uye dhigirii rekuparadzaniswa kweaviri ari pedyo maWeyl mapoinzi mu kz = 0 ndege.
FIG.4. Phototopological phase transition muTd-WTe2 ye linearly polarized light photon simba (?) ω) uye polarization direction (θ) inotsamira chikamu diagram
Nguva yekutumira: Sep-25-2023