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Band hybridization at the semimetal-semiconductor transition of Ta 2NiSe 5 enabled by mirror-symmetry breaking

Watson, Matthew D.; Marković, Igor; Morales, Edgar Abarca; Le Fèvre, Patrick; Merz, Michael; Haghighirad, Amir A.; King, Philip D. C.

Abstract (englisch):
We present a combined study from angle-resolved photoemission and density-functional-theory calculations of the temperature-dependent electronic structure in the excitonic insulator candidate Ta2NiSe5. Our experimental measurements unambiguously establish the normal state as a semimetal with a significant band overlap of >100 meV. Our temperature-dependent measurements indicate how these low-energy states hybridize when cooling through the well-known 327 K phase transition in this system. From our calculations and polarizationdependent photoemission measurements, we demonstrate the importance of a loss of mirror symmetry in enabling the band hybridization, driven by a shearlike structural distortion which reduces the crystal symmetry from orthorhombic to monoclinic. Our results thus point to the key role of the lattice distortion in enabling the phase transition of Ta2NiSe5.

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DOI: 10.1103/PhysRevResearch.2.013236
Zugehörige Institution(en) am KIT Institut für Quantenmaterialien und -technologien (IQMT)
Publikationstyp Zeitschriftenaufsatz
Publikationsdatum 02.03.2020
Sprache Englisch
Identifikator ISSN: 2643-1564
KITopen-ID: 1000117678
HGF-Programm 43.21.01 (POF III, LK 01)
Quantum Correlations in Condensed Matter
Erschienen in Physical review research
Band 2
Heft 1
Seiten Article no: 013236
Vorab online veröffentlicht am 29.02.2020
Schlagwörter Band hybridization at the semimetal-semiconductor; 2019-022-025949; 2020-024-029049 WERA
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