Sharp raman anomalies and broken adiabaticity at a pressure induced transition from band to topological insulator in Sb2Se3

Bera, Achintya and Pal, Koushik and Muthu, DVS and Sen, Somaditya and Guptasarma, Prasenjit and Waghmare, UV and Sood, AK (2013) Sharp raman anomalies and broken adiabaticity at a pressure induced transition from band to topological insulator in Sb2Se3. In: Physical Review Letters, 110 (10). 107401_1-107401_5.

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Abstract

The nontrivial electronic topology of a topological insulator is thus far known to display signatures in a robust metallic state at the surface. Here, we establish vibrational anomalies in Raman spectra of the bulk that signify changes in electronic topology: an E-g(2) phonon softens unusually and its linewidth exhibits an asymmetric peak at the pressure induced electronic topological transition (ETT) in Sb2Se3 crystal. Our first-principles calculations confirm the electronic transition from band to topological insulating state with reversal of parity of electronic bands passing through a metallic state at the ETT, but do not capture the phonon anomalies which involve breakdown of adiabatic approximation due to strongly coupled dynamics of phonons and electrons. Treating this within a four-band model of topological insulators, we elucidate how nonadiabatic renormalization of phonons constitutes readily measurable bulk signatures of an ETT, which will facilitate efforts to develop topological insulators by modifying a band insulator. DOI: 10.1103/PhysRevLett.110.107401

Item Type:	Journal Article
Publication:	Physical Review Letters
Publisher:	American Physical Society
Additional Information:	Copyright of this article belongs to American Physical Society.
Department/Centre:	Division of Physical & Mathematical Sciences > Physics
Date Deposited:	11 Apr 2013 05:30
Last Modified:	11 Apr 2013 05:30
URI:	http://eprints.iisc.ac.in/id/eprint/46308

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