Phononic soft mode behavior and a strong electronic background across the structural phase transition in the excitonic insulator Ta_{2}NiSe_{5}
Ta_{2}NiSe_{5} became one of the most investigated candidate materials for hosting an excitonic insulator ground state. Many studies describe the corresponding phase transition as a condensation of excitons breaking a continuous symmetry. This view got challenged recently pointing out the importance...
| Main Authors: | , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
American Physical Society
2020-12-01
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| Series: | Physical Review Research |
| Online Access: | http://doi.org/10.1103/PhysRevResearch.2.042039 |
| _version_ | 1827285920672382976 |
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| author | Min-Jae Kim Armin Schulz Tomohiro Takayama Masahiko Isobe Hidenori Takagi Stefan Kaiser |
| author_facet | Min-Jae Kim Armin Schulz Tomohiro Takayama Masahiko Isobe Hidenori Takagi Stefan Kaiser |
| author_sort | Min-Jae Kim |
| collection | DOAJ |
| description | Ta_{2}NiSe_{5} became one of the most investigated candidate materials for hosting an excitonic insulator ground state. Many studies describe the corresponding phase transition as a condensation of excitons breaking a continuous symmetry. This view got challenged recently pointing out the importance of the loss of two mirror symmetries at a structural phase transition that occurs together with the semiconductor—excitonic insulator transition. For such a scenario an unstable optical zone-center phonon at low energy is proposed to drive the transition. Here we report on the experimental observation of such a soft mode behavior using Raman spectroscopy. In addition we find a novel spectral feature, likely of electronic or joint electronic and phononic origin, that is clearly distinct from the lattice dynamics and that becomes dominant at T_{c}. This suggests a picture of joint structural and electronic orders driving the phase transition. |
| first_indexed | 2024-04-24T10:21:36Z |
| format | Article |
| id | doaj.art-619e2f6ff57a4e98bb67a4dacfe20f53 |
| institution | Directory Open Access Journal |
| issn | 2643-1564 |
| language | English |
| last_indexed | 2024-04-24T10:21:36Z |
| publishDate | 2020-12-01 |
| publisher | American Physical Society |
| record_format | Article |
| series | Physical Review Research |
| spelling | doaj.art-619e2f6ff57a4e98bb67a4dacfe20f532024-04-12T17:05:04ZengAmerican Physical SocietyPhysical Review Research2643-15642020-12-012404203910.1103/PhysRevResearch.2.042039Phononic soft mode behavior and a strong electronic background across the structural phase transition in the excitonic insulator Ta_{2}NiSe_{5}Min-Jae KimArmin SchulzTomohiro TakayamaMasahiko IsobeHidenori TakagiStefan KaiserTa_{2}NiSe_{5} became one of the most investigated candidate materials for hosting an excitonic insulator ground state. Many studies describe the corresponding phase transition as a condensation of excitons breaking a continuous symmetry. This view got challenged recently pointing out the importance of the loss of two mirror symmetries at a structural phase transition that occurs together with the semiconductor—excitonic insulator transition. For such a scenario an unstable optical zone-center phonon at low energy is proposed to drive the transition. Here we report on the experimental observation of such a soft mode behavior using Raman spectroscopy. In addition we find a novel spectral feature, likely of electronic or joint electronic and phononic origin, that is clearly distinct from the lattice dynamics and that becomes dominant at T_{c}. This suggests a picture of joint structural and electronic orders driving the phase transition.http://doi.org/10.1103/PhysRevResearch.2.042039 |
| spellingShingle | Min-Jae Kim Armin Schulz Tomohiro Takayama Masahiko Isobe Hidenori Takagi Stefan Kaiser Phononic soft mode behavior and a strong electronic background across the structural phase transition in the excitonic insulator Ta_{2}NiSe_{5} Physical Review Research |
| title | Phononic soft mode behavior and a strong electronic background across the structural phase transition in the excitonic insulator Ta_{2}NiSe_{5} |
| title_full | Phononic soft mode behavior and a strong electronic background across the structural phase transition in the excitonic insulator Ta_{2}NiSe_{5} |
| title_fullStr | Phononic soft mode behavior and a strong electronic background across the structural phase transition in the excitonic insulator Ta_{2}NiSe_{5} |
| title_full_unstemmed | Phononic soft mode behavior and a strong electronic background across the structural phase transition in the excitonic insulator Ta_{2}NiSe_{5} |
| title_short | Phononic soft mode behavior and a strong electronic background across the structural phase transition in the excitonic insulator Ta_{2}NiSe_{5} |
| title_sort | phononic soft mode behavior and a strong electronic background across the structural phase transition in the excitonic insulator ta 2 nise 5 |
| url | http://doi.org/10.1103/PhysRevResearch.2.042039 |
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