An sami ci gaba a cikin nazarin motsi mai sauri na Weil quasiparticles wanda ke sarrafa shi ta hanyarna'urorin laser
A cikin 'yan shekarun nan, binciken ka'idoji da gwaji kan yanayin kwantum da kayan kwantum na yanayin ƙasa ya zama babban batu a fannin kimiyyar lissafi mai rikitarwa. A matsayin sabon ra'ayi game da rarrabuwar abubuwa, tsarin topological, kamar daidaituwa, babban ra'ayi ne a cikin kimiyyar lissafi mai rikitarwa. Fahimtar topology yana da alaƙa da matsalolin asali a cikin kimiyyar lissafi mai rikitarwa, kamar tsarin lantarki na asalimatakan kwantum, sauye-sauyen yanayin kwantum da kuma motsa abubuwa da yawa da ba su motsa jiki a cikin matakan kwantum. A cikin kayan yanayin duniya, haɗin kai tsakanin matakai da yawa na 'yanci, kamar electrons, phonon da spin, yana taka muhimmiyar rawa wajen fahimtar da daidaita halayen abu. Ana iya amfani da hasken da ke motsa haske don bambance tsakanin hulɗa daban-daban da kuma sarrafa yanayin abu, kuma ana iya samun bayanai game da halayen zahiri na abu, sauye-sauyen yanayin tsari, da sabbin yanayin kwantum. A halin yanzu, dangantakar da ke tsakanin halayen macroscopic na kayan yanayin duniya da filin haske ke jagoranta da tsarin atom ɗinsu mai ƙananan ƙwayoyin cuta da kaddarorin lantarki ya zama burin bincike.
Halayyar amsawar lantarki ta kayan topological tana da alaƙa da tsarin lantarki mai ƙananan ƙwayoyin halitta. Ga semi-ƙarfe na topological, motsin mai ɗaukar kaya kusa da mahadar band yana da matuƙar tasiri ga halayen aikin raƙuman ruwa na tsarin. Nazarin abubuwan da ba su da layi a cikin semi-ƙarfe na topological na iya taimaka mana mu fahimci halayen zahiri na yanayin da ke cikin tsarin, kuma ana sa ran za a iya amfani da waɗannan tasirin wajen ƙerana'urorin ganida kuma ƙirar ƙwayoyin hasken rana, waɗanda ke samar da damar amfani da su a nan gaba. Misali, a cikin Weyl semi-metal, shan photon na hasken da aka yi da zagaye zai sa juyawar ta juya, kuma domin a cimma kiyaye ƙarfin kusurwa, za a rarraba motsin lantarki a ɓangarorin biyu na mazubin Weyl ba tare da daidaito ba tare da la'akari da yadda aka rarraba hasken da aka yi da zagaye, wanda ake kira dokar zaɓin chiral (Hoto na 1).
Nazarin ka'idar abubuwan da suka faru na gani marasa layi na kayan topological yawanci yana amfani da hanyar haɗa lissafin halayen yanayin ƙasa na abu da nazarin daidaito. Duk da haka, wannan hanyar tana da wasu lahani: ba ta da bayanai masu ƙarfi na ainihin lokaci na masu ɗaukar kaya masu farin ciki a cikin sararin motsi da sararin samaniya na gaske, kuma ba za ta iya kafa kwatancen kai tsaye da hanyar gano gwaji da aka warware lokaci ba. Ba za a iya la'akari da haɗin kai tsakanin electron-phonons da photon-phonons ba. Kuma wannan yana da mahimmanci don wasu sauye-sauye na lokaci su faru. Bugu da ƙari, wannan nazarin ka'idar da aka dogara da ka'idar rikicewa ba zai iya magance hanyoyin zahiri a ƙarƙashin filin haske mai ƙarfi ba. Kwaikwayon ƙwayoyin halitta masu aiki da yawa (TDDFT-MD) bisa ƙa'idodin farko zai iya magance matsalolin da ke sama.
Kwanan nan, a ƙarƙashin jagorancin mai bincike Meng Sheng, mai binciken digiri na biyu Guan Mengxue da ɗalibin digiri na uku Wang En na ƙungiyar SF10 ta Babban Dakin Gwaji na Jiha na Kimiyyar Surface na Cibiyar Kimiyya ta Kwalejin Kimiyya ta China/Cibiyar Bincike ta Ƙasa ta Beijing don Kimiyyar Matter Mai Haɗaka, tare da haɗin gwiwar Farfesa Sun Jiatao na Cibiyar Fasaha ta Beijing, sun yi amfani da software na kwaikwayon yanayin motsi na jihar da aka haɓaka da kansa. An binciki halayen amsawar motsin rai na quastiparticle zuwa laser mai sauri a cikin nau'in Weyl semi-metal WTe2 na biyu.
An nuna cewa zaɓaɓɓen motsin da ke ɗauke da na'urori kusa da wurin Weyl ana tantance shi ta hanyar daidaita yanayin orbital na atomic da ƙa'idar zaɓin canji, wanda ya bambanta da ƙa'idar zaɓin juyawa ta yau da kullun don motsin chiral, kuma ana iya sarrafa hanyar motsawar ta ta hanyar canza alkiblar watsa haske na haske mai layi da makamashin photon (Hoto na 2).
Ƙarfin da ba shi da daidaito na masu ɗaukar kaya yana haifar da kwararar hoto a hanyoyi daban-daban a cikin sararin samaniya na gaske, wanda ke shafar alkibla da daidaito na zamewar layin tsakanin tsarin. Tunda halayen yanayin WTe2, kamar adadin maki Weyl da matakin rabuwa a cikin sararin motsi, sun dogara sosai akan daidaiton tsarin (Hoto na 3), ƙarfin da ba shi da daidaituwa na masu ɗaukar kaya zai haifar da halaye daban-daban na Weyl quastiparticles a cikin sararin motsi da canje-canje masu dacewa a cikin halayen yanayin tsarin. Don haka, binciken ya ba da zane mai haske na lokaci don sauye-sauyen lokaci na hoto (Hoto na 4).
Sakamakon ya nuna cewa ya kamata a kula da yanayin motsin jiki na mai ɗaukar kaya kusa da wurin Weyl, kuma ya kamata a yi nazarin halayen orbital na aikin raƙuman ruwa. Tasirin su biyun sun yi kama da juna amma a bayyane yake cewa tsarin ya bambanta, wanda ke ba da tushen ka'ida don bayyana keɓancewar maki Weyl. Bugu da ƙari, hanyar lissafi da aka ɗauka a cikin wannan binciken na iya fahimtar hulɗar da ke da sarkakiya da halayen motsi a matakan atomic da electronic a cikin sikelin lokaci mai sauri, yana bayyana hanyoyin microphysical ɗinsu, kuma ana sa ran zai zama kayan aiki mai ƙarfi don bincike na gaba kan abubuwan gani marasa layi a cikin kayan topological.
Sakamakon binciken yana cikin mujallar Nature Communications. Aikin binciken yana samun goyon bayan Shirin Bincike da Ci Gaban Kasa, Gidauniyar Kimiyyar Halitta ta Kasa da kuma Shirin Gwaji na Dabaru (Rukunin B) na Kwalejin Kimiyya ta kasar Sin.
FIG.1.a. Dokar zaɓin chirality don maki Weyl tare da alamar chirality mai kyau (χ=+1) a ƙarƙashin hasken da'ira mai rabewa; Ƙarfin zaɓi saboda daidaiton orbital na atomic a wurin Weyl na b. χ=+1 a cikin hasken polarized akan layi
FIG. 2. Zane-zanen tsarin atom na a, Td-WTe2; b. Tsarin madauri kusa da saman Fermi; (c) Tsarin madauri da gudummawar dangi na orbital na atomic da aka rarraba a kan layuka masu tsayi a yankin Brillouin, kibiyoyi (1) da (2) suna wakiltar motsawa kusa ko nesa da wuraren Weyl, bi da bi; d. Ƙara girman tsarin madauri tare da alkiblar Gamma-X
FIG.3.ab: An kwatanta motsin tsakanin layukan da ke tsakanin alkiblar haske mai layi tare da axis na A da B na lu'ulu'u, da kuma yanayin motsi mai dacewa; C. Kwatanta tsakanin kwaikwayon ka'ida da lura da gwaji; de: Juyin halittar simmetri na tsarin da matsayi, lamba da matakin rabuwar maki biyu mafi kusa na Weyl a cikin jirgin kz=0
FIG. 4. Sauyin yanayin hoto a cikin Td-WTe2 don kuzarin hasken photon mai layi mai rabewa (?) ω) da kuma zane mai dogara da yanayin polarization (θ)
Lokacin Saƙo: Satumba-25-2023