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تسجيل مستخدم جديدComment on Direct observation of excitonic instability in Ta$_2$NiSe$_5$ [arXiv:2007.08212 (2020)]
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G. Blumberg
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The origin of the second order phase transition at 328K in Ta$_2$NiSe$_5$, a prominent candidate for direct gap excitonic insulator, remains under fervent debate. The driving force for the transition can be revealed by identification of the soft modes origin that may be deducted from polarization resolved Raman scattering experiments. Such studies were recently reported in [arXiv:2007.07344 (2020)], [arXiv:2102.07912 (2021)], [arXiv:2007.01723 (2020)] and [arXiv:2007.08212 (2020)]. In this Comment, it is shown that the parameters derived in a recent arXiv by Kwangrae Kim et. al. [arXiv:2007.08212 (2020)], including the Weiss temperature for excitonic transition, are based on inconsistent data.
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The microscopic quantum interference associated with excitonic condensation in Ta$_2$NiSe$_5$ is studied in the BCS-type mean-field approximation. We show that in ultrasonic attenuation the coherence peak appears just below the transition temperature
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