2021/03/25 by Yuan-Shan Zhang, J. A. N. Bruin, Jan A. N. Bruin +5 · 10 citations
Chemistry · Engineering · Materials Science · Physics and Astronomy · #2D Materials and Applications #Chalcogenide Semiconductor Thin Films #Chemistry #Condensed matter physics #Crystallography #Materials science #Perovskite Materials and Applications #Phonon #Physics #cond-mat.str-el
paper · pdf · doi:10.1103/physrevb.104.l121201
published in Physical review. B./Physical review. B 104(12) (American Physical Society)
arxiv created 2021/03/25 · openalex publication_date 2021/09/17 · arxiv updated 2021/09/22 · openalex created_date 2021/09/27 · openalex updated_date 2026/07/22
The quasi-one-dimensional layered compound Ta2NiSe5 has been proposed to undergo a transition to an excitonic insulator at Tc=326 K. We found a clear anomaly at Tc in the in-plane thermal conductivities both parallel (\ensuremath∥\phantom\rule4pt0exa) and perpendicular (\ensuremath∥\phantom\rule4pt0exc) to the one-dimensional chains, \ensuremathκa and \ensuremathκc. While \ensuremathκa shows a rapid decrease below Tc, \ensuremathκc shows a pronounced V-shaped suppression centered at Tc. We argue that the decrease of \ensuremathκa represents the suppression of the quasiparticle contribution below Tc due to the excitonic transition. On the other hand, the V-shaped suppression of \ensuremathκc comes from the enhanced phonon scattering by soft phonons associated with the monoclinic transition with momentum q\ensuremath∥c. The continued suppression of \ensuremathκc up to an extremely high temperature above Tc suggests the persistence of phonon softening likely coupled to electronic, presumably excitonic, fluctuations.