An sami ci gaba a cikin binciken ultrafast motsi na Weil quasiparticles sarrafawa taLaser
A cikin 'yan shekarun nan, bincike na ka'idar da gwaji kan jihohin kididdigar topological da kayan kidaddigar topological ya zama batu mai zafi a fagen ilimin kimiyyar kwayoyin halitta. A matsayin sabon ra'ayi na rarrabuwar kwayoyin halitta, tsari na topological, kamar simmetry, shine babban ra'ayi a cikin kimiyar kwayoyin halitta. Zurfafa fahimtar topology yana da alaƙa da ainihin matsalolin a cikin ilimin kimiyyar kwayoyin halitta, kamar ainihin tsarin lantarki namatakan ƙididdiga, Juyin juzu'i na jimla da tashin hankali na abubuwa da yawa marasa motsi a cikin matakan ƙididdiga. A cikin kayan aikin topological, haɗin kai tsakanin digiri na yanci da yawa, kamar su electrons, phonons da spin, suna taka muhimmiyar rawa wajen fahimta da daidaita kayan abu. Za a iya amfani da zumuwar haske don bambance tsakanin mu'amala daban-daban da sarrafa yanayin kwayoyin halitta, sannan za'a iya samun bayanai game da ainihin kayan aikin zahiri, sauye-sauyen tsari, da sabbin jihohin adadi. A halin yanzu, dangantakar da ke tsakanin halayen macroscopic na kayan topological wanda filin haske ke motsawa da tsarin su na atomatik da kuma kayan lantarki ya zama makasudin bincike.
Halin amsawar hoto na kayan topological yana da alaƙa da kusanci da tsarin lantarki da ba a iya gani ba. Don ƙananan karafa na topological, tashin hankali mai ɗaukar hoto kusa da mahadar band ɗin yana da matukar damuwa ga halayen aikin igiyar ruwa na tsarin. Binciken abubuwan da ba a iya gani ba a cikin ƙananan ƙarfe na topological na iya taimaka mana mu fahimci kaddarorin jiki na jihohin da ke da sha'awar tsarin, kuma ana sa ran za a iya amfani da waɗannan tasirin a cikin kera nana'urorin ganida kuma ƙirar ƙwayoyin hasken rana, samar da yuwuwar aikace-aikace masu amfani a nan gaba. Misali, a cikin karfen karfe na Weyl, shan photon na haske mai madauwari, zai haifar da jujjuyawar, kuma domin a samu ci gaba da kiyaye karfin angular, za a rarraba kuzarin lantarki a bangarorin biyu na mazugi na Weyl ba daidai ba. Jagoran yaduwar haske mai da'ira, wanda ake kira ka'idar zaɓin chiral (Hoto 1).
Nazarin ka'idar abubuwan al'amuran gani mara kyau na kayan topological yawanci yana ɗaukar hanyar haɗa lissafin kaddarorin kadarori na ƙasa da ƙididdigar ƙima. Duk da haka, wannan hanya tana da wasu lahani: ba ta da cikakken bayani mai ƙarfi na masu ɗaukar kaya masu sha'awa a cikin sararin samaniya da sararin samaniya, kuma ba za ta iya kafa kwatancen kai tsaye tare da hanyar gano gwajin da aka warware ba. Ba za a iya la'akari da haɗin kai tsakanin phonon-electronics da photon-phonons ba. Kuma wannan yana da mahimmanci ga wasu canje-canjen lokaci su faru. Bugu da ƙari, wannan bincike na ka'idar bisa ka'idar rikice-rikice ba zai iya magance tsarin jiki a ƙarƙashin filin haske mai ƙarfi ba. Ƙwararren ƙwararrun ƙwayoyin ƙwayoyin cuta masu dogaro da lokaci (TDDFT-MD) bisa ƙa'idodin farko na iya magance matsalolin da ke sama.
Kwanan nan, karkashin jagorancin mai bincike Meng Sheng, mai bincike na gaba da digiri na biyu Guan Mengxue da dalibin digiri na uku Wang En na rukunin SF10 na dakin gwaje-gwaje na mahimmin ilimin kimiyyar sararin samaniya na kwalejin kimiyyar lissafi na Kwalejin Kimiyya ta kasar Sin/Cibiyar bincike ta kasa ta Beijing don tattara al'amura. Physics, tare da haɗin gwiwar Farfesa Sun Jiatao na Cibiyar Fasaha ta Beijing, sun yi amfani da software na TDAP mai cike da farin ciki na jihar. An bincika halayen amsawar tashin hankali na quastiparticle zuwa laser ultrafast a cikin nau'i na biyu na Weyl Semi-metal WTe2.
An nuna cewa zaɓaɓɓen tashin hankali na masu ɗaukar kaya kusa da ma'anar Weyl an ƙaddara ta hanyar atom orbital symmetry da ka'idar zaɓin canji, wanda ya bambanta da tsarin zaɓin zaɓi na yau da kullun don tashin hankali na chiral, kuma ana iya sarrafa hanyar tashin hankali ta hanyar canza hanyar polarization. na hasken wutar lantarki na layi da kuma makamashin photon (FIG. 2).
Ƙaunar asymmetric na masu ɗaukar hoto suna haifar da hotunan hoto a wurare daban-daban a cikin sararin samaniya, wanda ke rinjayar shugabanci da kuma daidaitawar tsaka-tsakin tsaka-tsakin tsarin. Tun da topological Properties na WTe2, kamar adadin Weyl maki da kuma mataki na rabuwa a cikin hanzari sarari, sun dogara sosai a kan daidaita tsarin (Figure 3), da asymmetric excitation na masu dako zai kawo game da daban-daban hali na Weyl. quastiparticles a cikin sararin samaniya da kuma daidaitattun canje-canje a cikin abubuwan topological na tsarin. Don haka, binciken yana ba da ƙayyadaddun zane na lokaci don sauye-sauyen lokaci na phototopological (Hoto na 4).
Sakamakon ya nuna cewa ya kamata a mai da hankali ga chirality na tashin hankali mai ɗaukar kaya kusa da filin Weyl, kuma ya kamata a yi nazarin kaddarorin kwayoyin orbital na aikin igiyar ruwa. Tasirin biyun yana kama da juna amma tsarin yana da bambanci a fili, wanda ke ba da tushe na ka'idar don bayyana ma'anar ma'anar Weyl. Bugu da ƙari, hanyar ƙididdigewa da aka karɓa a cikin wannan binciken na iya zurfin fahimtar hadaddun mu'amala da halayen motsa jiki a matakan atomic da lantarki a cikin ma'aunin lokaci mai sauri, bayyana hanyoyin su na microphysical, kuma ana sa ran zama kayan aiki mai ƙarfi don bincike na gaba akan. abubuwan da ba na kan layi ba a cikin kayan topological.
Sakamakon yana cikin mujallar Nature Communications. Aikin binciken yana samun goyon bayan shirin mahimmin bincike da ci gaba na kasa, da gidauniyar kimiyyar dabi'a ta kasa da kuma shirin gwaji mai dabara (Kashi B) na kwalejin kimiyyar kasar Sin.
FIG.1.a. Ka'idar zaɓin chirality don maki Weyl tare da ingantacciyar alamar chirality (χ=+1) ƙarƙashin haske mai madauwari; Zaɓen tashin hankali saboda atom ɗin orbital symmetry a wurin Weyl na b. χ=+1 a cikin hasken wuta na kan layi
FIG. 2. Tsarin tsarin atomatik na a, Td-WTe2; b. Tsarin bandeji kusa da saman Fermi; (c) Tsarin rukuni da gudunmawar dangi na orbitals na atomic da aka rarraba tare da manyan layukan simmetric a cikin yankin Brillouin, kibau (1) da (2) suna wakiltar tashin hankali kusa ko nesa da maki Weyl, bi da bi; d. Ƙaddamar da tsarin band tare da hanyar Gamma-X
FIG.3.ab: Ƙaƙwalwar dangi na motsi na layi na layi na polarized haske polarization shugabanci tare da A-axis da B-axis na crystal, kuma an kwatanta yanayin motsi daidai; C. Kwatanta tsakanin simintin ka'idar da kuma lura da gwaji; de: Juyin halittar tsarin da matsayi, lamba da matakin rabuwa na maki biyu na Weyl mafi kusa a cikin kz=0 jirgin sama.
FIG. 4. Canjin lokaci na Phototopological a cikin Td-WTe2 don samar da makamashin hasken wutar lantarki na layi-layi (?) ω) da jagorar polarization (θ) zane mai dogaro na lokaci
Lokacin aikawa: Satumba-25-2023