Enweela ọganihu n'ọmụmụ ihe ultrafast ngagharị nke Weil quasiparticles nke lasers na-achịkwa

Emeela ọganihu n'ọmụmụ ihe ultrafast ngagharị nke Weil quasiparticles na-achịkwalasers

N'ime afọ ndị na-adịbeghị anya, nyocha usoro mmụta na nnwale na steeti quantum topological na topological quantum material aghọwo isiokwu na-ekpo ọkụ na ngalaba nke condensed matter physics. Dị ka echiche ọhụrụ nke nhazi okwu, usoro topological, dị ka symmetry, bụ echiche bụ isi na physics okwu condensed. Nghọta miri emi nke topology metụtara nsogbu ndị bụ isi na physics okwu condensed, dị ka usoro eletrọnịkị bụ isi nkeusoro nke quantum, Ntugharị akụkụ nke quantum na mkpali nke ọtụtụ ihe anaghị emegharị ahụ n'usoro nke quantum. N'ihe gbasara topological, njikọ dị n'etiti ọtụtụ ogo nnwere onwe, dị ka electrons, phonons na spin, na-arụ ọrụ dị mkpa n'ịghọta na ịhazi ihe onwunwe. Enwere ike iji mkpali ọkụ mata ọdịiche dị n'etiti mmekọrịta dị iche iche na ịchịkwa ọnọdụ nke ihe ahụ, wee nweta ozi gbasara njirimara anụ ahụ bụ isi nke ihe ahụ, ntụgharị usoro nhazi, na steeti quantum ọhụrụ. Ka ọ dị ugbu a, mmekọrịta dị n'etiti omume macroscopic nke ihe topological nke ọkụ ọkụ na-ebugharị na usoro atomiki microscopic ha na akụrụngwa eletrọnịkị aghọwo ihe mgbaru ọsọ nyocha.

Omume mmeghachi omume fotoelectric nke ihe topological nwere njikọ chiri anya na usoro eletrọnịkị ya dị obere. N'ihi na topological ọkara ọla, ndị na-ebu excitation n'akụkụ bandwit intersection na-enwe mmetụta nke ukwuu na ife ọrụ àgwà nke usoro. Ọmụmụ ihe na-ahụ anya na-adịghị ahụ anya na topological semi-metals nwere ike inyere anyị aka ịghọta nke ọma ihe anụ ahụ nke steeti obi ụtọ nke usoro ahụ, na a na-atụ anya na enwere ike iji mmetụta ndị a mee ihe na mmepụta nkengwa anya ngwaọrụna imewe nke mkpụrụ ndụ anyanwụ, na-enye ngwa ndị nwere ike ime n'ọdịnihu. Dịka ọmụmaatụ, n'ime igwe igwe nke Weyl, ịmịnye foton nke ọkụ na-agba gburugburu ga-eme ka ọkpụkpụ ahụ tụgharịa, na iji zute nchekwa nke oge angular, a ga-ekesa mkpali electron n'akụkụ abụọ nke cone Weyl n'ụzọ na-adịghị mma. ntụzịaka nke mgbasa ọkụ nke okirikiri polarized, nke a na-akpọ iwu nhọrọ chiral (Njirimara 1).

The theoretical ọmụmụ nke nononlinear ngwa anya phenomena nke topological ihe na-emekarị nakweere usoro nke ijikọta ngụkọta oge nke ihe ala ala Njirimara na symmetry analysis. Otú ọ dị, usoro a nwere ụfọdụ ntụpọ: ọ na-enweghị ezigbo oge ozi ike nke ndị na-ebu na-enwe obi ụtọ na ohere na-agba ọsọ na ezigbo ohere, ọ nweghịkwa ike ịmepụta ntụnyere kpọmkwem na usoro nchọpụta nyocha nke edoziworo oge. Enweghị ike ịtụle njikọ dị n'etiti phonon electron na foton-phonons. Na nke a dị oke mkpa maka mgbanwe ụfọdụ nke usoro ga-eme. Tụkwasị na nke a, nyocha usoro ihe omimi a na-adabere n'echiche mgbagwoju anya enweghị ike ịme usoro anụ ahụ n'okpuru ebe ọkụ siri ike. Ngwunye njupụta arụ ọrụ molecular dynamics (TDDFT-MD) dabere na oge dabere na ụkpụrụ mbụ nwere ike idozi nsogbu ndị a dị n'elu.

Na nso nso a, n'okpuru nduzi nke onye nchọpụta Meng Sheng, onye nyocha postdoctoral Guan Mengxue na nwa akwụkwọ doctoral Wang En nke SF10 Group nke State Key Laboratory of Surface Physics nke Institute of Physics nke Chinese Academy of Sciences/Beijing National Research Center for Concentrated Matter Physics, na mmekorita ya na Prọfesọ Sun Jiatao nke Institutelọ Ọrụ Nkà na Ụzụ nke Beijing, ha jiri sọftụwia simulation steeti TDAP nke nwere obi ụtọ mebere onwe ya. A na-enyocha njirimara nzaghachi nke quastiparticle excitation na ultrafast laser na ụdị nke abụọ nke Weyl semi-metal WTe2.

E gosiputara na nhọpụta nhọrọ nke ndị na-ebu ndị na-ebu n'akụkụ ebe Weyl na-ekpebi site na atomic orbital symmetry na iwu nhọrọ mgbanwe, nke dị iche na usoro nhọrọ ntụgharị nke a na-emebu maka excitation chiral, na ụzọ mkpali ya nwere ike ịchịkwa site n'ịgbanwe ntụgharị polarization. nke linearly polarized ìhè na photon ike (FIG. 2).

Mkparịta ụka asymmetric nke ndị na-ebu na-eme ka photocurrents dị n'akụkụ dị iche iche dị na mbara igwe, nke na-emetụta ntụziaka na symmetry nke interlayer slip of the system. Ebe ọ bụ na topological Njirimara nke WTe2, dị ka ọnụ ọgụgụ nke Weyl isi na ogo nke nkewa na ngwa ngwa ohere, na-ukwuu dabere na symmetry nke usoro (Figure 3), asymmetric excitation nke ndị na-ebu ga-eme ka omume dị iche iche nke Weyl. quastiparticles na oghere ọkụ ọkụ na mgbanwe kwekọrọ na njirimara topological nke usoro ahụ. Ya mere, ọmụmụ ihe ahụ na-enye ihe ngosi nke oge doro anya maka mgbanwe mgbanwe oge fototopological (Fig 4).

Nsonaazụ na-egosi na ekwesịrị itinye uche na chirality nke mkpali ụgbọelu dị nso na Weyl point, na ekwesịrị nyochaa njirimara orbital atọm nke ọrụ ebili mmiri. Mmetụta nke abụọ ahụ yiri ma usoro ahụ doro anya na ọ dị iche, nke na-enye usoro ihe ndabere maka ịkọwa ihe dị iche iche nke isi ihe Weyl. Na mgbakwunye, usoro mgbakọ na mwepụ a nakweere n'ọmụmụ ihe a nwere ike ịghọta nke ọma mmekọrịta dị mgbagwoju anya na omume na-agbanwe agbanwe na atomiki na eletrọnịkị n'ogo oge dị oke ngwa ngwa, na-ekpughe usoro microphysical ha, a na-atụkwa anya na ọ ga-abụ ngwá ọrụ dị ike maka nyocha n'ọdịnihu na ihe ngosi anya na-adịghị adị n'ime ihe topological.

Nsonaazụ dị na akwụkwọ akụkọ Nature Communications. A na-akwado ọrụ nyocha ahụ site na National Key Research and Development Plan, National Natural Science Foundation na Strategic Pilot Project (Aka B) nke Ụlọ Akwụkwọ Ọmụmụ sayensị nke China.

FIG.1.a. Iwu nhọrọ chirality maka isi Weyl nwere akara chirality dị mma (χ=+1) n'okpuru ọkụ nwere okirikiri; Mmasị ahọpụtara n'ihi symmetry orbital atomic na ebe Weyl nke b. χ=+1 n'ọkụ dị n'ịntanetị

FIG. 2. Atọmk Ọdịdị eserese nke a, Td-WTe2; b. Ihe owuwu band dị nso n'elu Fermi; (c) Nhazi otu na onyinye ikwu nke atomic orbitals kesara n'akụkụ ahịrị symmetric dị elu na mpaghara Brillouin, akụ (1) na (2) na-anọchi anya mkpali dị nso ma ọ bụ dị anya site na isi Weyl, otu; d. Mmụba nke nhazi band n'akụkụ ụzọ Gamma-X

FIG.3.ab: The ikwu interlayer ije nke linearly polarized ìhè polarization direction tinyere A-axis na B-axis nke crystal, na kwekọrọ ekwekọ ije mode na-egosi; C. Ntụnyere n'etiti simulation usoro ihe omume na nlele nnwale; de: Symmetry evolushọn nke usoro na ọnọdụ, ọnụ ọgụgụ na ogo nkewa nke abụọ Weyl isi na kz = 0 ụgbọ elu.

FIG. 4. Phototopological oge mgbanwe na Td-WTe2 maka linearly polarized ìhè photon ike (?) ω) na polarization direction (θ) dabere na eserese eserese.