Transition from a metal to a massless-Dirac-fermion phase in an organic conductor investigated by 13C NMR

Kazuya Miyagawa, Yohta Sata, Tomotaka Taniguchi, Michihiro Hirata, Dong Liu, Masafumi Tamura, Kazushi Kanoda

Research output: Contribution to journalArticle

Abstract

The θ-(BEDT-TTF)2I3 system is suggested to be the second organic system of massless Dirac fermions, which emerge from the metallic phase at a pressure exceeding 5 kbar. We have performed 13C NMR measurements on a single crystal of θ-(BEDT-TTF)2I3 under variable pressure across the critical pressure, 5 kbar. The Knight shift and spin-lattice relaxation rate show that a metallic state with an NMR enhancement factor of 2.2-2.4 at ambient pressure persists up to the critical pressure of 5 kbar. Above that, a marked spectral change indicative of a first-order phase transition is found. The angular dependence of NMR spectra indicates a structural phase transition from the θ-type molecular arrangement to the α-type one, which hosts the tilted Dirac cone.

Original languageEnglish
Article number073710
Journaljournal of the physical society of japan
Volume85
Issue number7
DOIs
Publication statusPublished - 2016 Jul 15

ASJC Scopus subject areas

  • Physics and Astronomy(all)

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