Kupita patsogolo kwapangidwa pophunzira za ultrafast motion wa Weil quasiparticles olamulidwa ndilasers
M'zaka zaposachedwa, kafukufuku wazongopeka komanso woyesera pa topological quantum states ndi topological quantum zida zakhala mutu wovuta kwambiri pankhani ya fiziki ya condensed matter.Monga lingaliro latsopano la gulu la zinthu, dongosolo la topological, monga symmetry, ndi lingaliro lofunikira mu fizikiki yofupikitsidwa.Kumvetsetsa kwakuya kwa topology kumakhudzana ndi zovuta zoyambira mu fizikisi ya zinthu zofupikitsidwa, monga maziko amagetsi amagawo a quantum, kusintha kwa gawo la quantum ndi chisangalalo cha zinthu zambiri zosasunthika mu magawo a quantum.Muzinthu zakuthambo, kulumikizana pakati pa magawo ambiri aufulu, monga ma elekitironi, ma phononi ndi ma spin, amatenga gawo lalikulu pakumvetsetsa ndikuwongolera zinthu zakuthupi.Kusangalatsa kopepuka kungagwiritsidwe ntchito kusiyanitsa pakati pa kuyanjana kosiyanasiyana ndikuwongolera momwe zinthu zilili, ndipo chidziwitso chokhudza zinthu zoyambira zakuthupi, kusintha kwamagawo, ndi mayiko atsopano a quantum zitha kupezeka.Pakalipano, ubale pakati pa machitidwe a macroscopic a zinthu zakuthambo zoyendetsedwa ndi kuwala ndi mawonekedwe awo a atomiki ang'onoang'ono ndi zinthu zamagetsi wakhala cholinga chofufuza.
Mawonekedwe a ma photoelectric a zinthu zakuthambo amagwirizana kwambiri ndi mawonekedwe ake amagetsi ang'onoang'ono.Kwa topological semi-metals, chonyamulira chonyamulira pafupi ndi mphambano ya bandi chimakhudzidwa kwambiri ndi mawonekedwe a magwiridwe antchito a dongosolo.Kuphunzira kwa zochitika zosawoneka bwino mu topological semi-metals kungatithandize kumvetsetsa bwino zakuthupi zamayiko okondwa a dongosolo, ndipo zikuyembekezeka kuti izi zitha kugwiritsidwa ntchito popangazida zowonerandi mapangidwe a ma cell a dzuwa, omwe angapereke ntchito zothandiza m'tsogolomu.Mwachitsanzo, mu Weyl semi-metal, kuyamwa fotoni ya kuwala kozungulira kozungulira kumapangitsa kuti kupindika kugwedezeke, ndipo kuti mukwaniritse kusungika kwamphamvu ya angular, chisangalalo cha elekitironi kumbali zonse ziwiri za Weyl chulucho chidzagawidwa mosagwirizana. mayendedwe a circularly polarized light propagation, yomwe imatchedwa lamulo la kusankha chiral (Chithunzi 1).
Kufufuza kwachidziwitso cha zochitika zosaoneka bwino za zinthu zakuthambo nthawi zambiri kumatenga njira yophatikizira kuwerengera kwa zinthu zapansi panthaka ndi kusanthula kofanana.Komabe, njirayi ili ndi zolakwika zina: ilibe chidziwitso cha nthawi yeniyeni ya zonyamulira zokondwa mu malo othamanga ndi malo enieni, ndipo sichikhoza kukhazikitsa kufananitsa kwachindunji ndi njira yodziwira zoyesera nthawi.Kulumikizana pakati pa ma electron-phononi ndi ma photon-phononi sikungaganizidwe.Ndipo izi ndizofunikira kwambiri kuti magawo ena asinthe.Kuonjezera apo, kusanthula kwachidziwitso ichi kutengera chiphunzitso chosokoneza sikungathe kulimbana ndi zochitika zakuthupi pansi pa kuwala kolimba.Kuyerekeza kwanthawi yodalira kachulukidwe kachulukidwe ka molekyulu (TDDFT-MD) kutengera mfundo zoyambirira kumatha kuthana ndi mavutowa.
Posachedwapa, motsogozedwa ndi wofufuza Meng Sheng, wofufuza pambuyo pa udotolo Guan Mengxue ndi wophunzira udokotala Wang En wa SF10 Gulu la State Key Laboratory of Surface Physics ya Institute of Physics ya Chinese Academy of Sciences/Beijing National Research Center for Concentrated Matter Fizikisi, mogwirizana ndi Pulofesa Sun Jiatao wa Beijing Institute of Technology, adagwiritsa ntchito pulogalamu yodzipangira yokha yosangalatsa ya TDAP.Makhalidwe oyankha a quastiparticle excitation to ultrafast laser mu mtundu wachiwiri wa Weyl semi-metal WTe2 amafufuzidwa.
Zasonyezedwa kuti chisangalalo chosankha cha zonyamulira pafupi ndi Weyl point chimatsimikiziridwa ndi atomic orbital symmetry ndi lamulo la kusintha kwa kusintha, lomwe ndi losiyana ndi lamulo lachizoloŵezi losankhira mapiko a chiral excitation, ndipo njira yake yosangalatsa imatha kuwongoleredwa mwa kusintha njira ya polarization. ya linearly polarized kuwala ndi photon mphamvu (FIG. 2).
The asymmetric chisangalalo cha zonyamulira iduces photocurrents mbali zosiyanasiyana mu danga lenileni, zomwe zimakhudza malangizo ndi symmetry wa interlayer slip wa dongosolo.Popeza kuti zinthu zakuthambo za WTe2, monga kuchuluka kwa mfundo za Weyl komanso kuchuluka kwa kulekanitsidwa kwanthawi yayitali, zimadalira kwambiri ma symmetry a dongosolo (Chithunzi 3), chisangalalo cha asymmetric cha onyamula chidzabweretsa machitidwe osiyanasiyana a Weyl. quastiparticles mu liwiro danga ndi lolingana kusintha katundu topological dongosolo.Choncho, phunziroli limapereka chithunzi chomveka bwino cha kusintha kwa gawo la phototopological (Chithunzi 4).
Zotsatira zikuwonetsa kuti kusangalatsa kwa chisangalalo cha chonyamulira pafupi ndi Weyl point kuyenera kutsatiridwa, ndipo mawonekedwe a atomiki a ntchito yamafunde ayenera kuwunikidwa.Zotsatira za awiriwa ndizofanana koma makinawo mwachiwonekere ndi osiyana, omwe amapereka maziko amalingaliro ofotokozera kuphatikizika kwa mfundo za Weyl.Kuphatikiza apo, njira yowerengera yomwe yatengedwa mu phunziroli imatha kumvetsetsa mwakuya kuyanjana kovutirapo komanso machitidwe osinthika pamilingo ya atomiki ndi zamagetsi pamlingo wothamanga kwambiri, kuwulula njira zawo zama microphysical, ndipo ikuyembekezeka kukhala chida champhamvu pakufufuza kwamtsogolo zochitika zopanda mawonekedwe muzinthu zakuthambo.
Zotsatira zili m'magazini ya Nature Communications.Ntchito yofufuzira imathandizidwa ndi National Key Research and Development Plan, National Natural Science Foundation ndi Strategic Pilot Project (Gawo B) la Chinese Academy of Sciences.
MFUNDO.1.a.Lamulo losankhira chirality pamagawo a Weyl okhala ndi chizindikiro chabwino (χ=+1) pansi pa kuwala kozungulira kozungulira;Chisangalalo chosankha chifukwa cha ma atomiki orbital symmetry pa Weyl point ya b.χ=+1 mu kuwala kwa polarized pa intaneti
CHITH.2. Chithunzi cha ma atomiki a, Td-WTe2;b.Kapangidwe ka band pafupi ndi Fermi pamwamba;(c) Maonekedwe a bandi ndi zopereka zofananira za orbital za atomiki zogawidwa m'mizere yofanana kwambiri m'chigawo cha Brillouin, mivi (1) ndi (2) imayimira chisangalalo pafupi kapena kutali ndi malo a Weyl, motsatana;d.Kukulitsa mawonekedwe a bandi motsatira njira ya Gamma-X
FIG.3.ab: Kuyenda kwapakati pamtundu wa polarized polarization direction of the linearly polarized light polarization direction of the A-axis and B-axis of the crystal, ndi njira yoyendera yofananira ikuwonetsedwa;C. Kuyerekeza pakati pa kayeseleledwe kamalingaliro ndi kuwunika koyeserera;de: Chisinthiko cha Symmetry cha dongosolo ndi malo, chiwerengero ndi digiri ya kulekana kwa mfundo ziwiri zapafupi za Weyl mu kz=0 ndege
CHITH.4. Kusintha kwa gawo la Phototopological mu Td-WTe2 kwa mphamvu yowunikira yowunikira (?) ω) ndi polarization direction (θ) chithunzi chodalira
Nthawi yotumiza: Sep-25-2023