Observation of three-dimensional Dirac semimetal state in topological insulator Bi2Se3

Abstract

The three dimensional (3D) topological insulators are predicted to exhibit a 3D Dirac semimetal state in critical regime of topological to trivial phase transition. Here we demonstrate the first experimental evidence of 3D Dirac semimetal state in topological insulator Bi2Se3 with bulk carrier concentration of ~ 10^19 cm^{-3}, using magneto-transport measurements. At low temperatures, the resistivity of our Bi2Se3 crystal exhibits clear Shubnikov-de Haas (SdH) oscillations above 6T. The analysis of these oscillations through Lifshitz-Onsanger and Lifshitz-Kosevich theory reveals a non-trivial pi Berry phase coming from 3D bands, which is a decisive signature of 3D Dirac semimetal state. The large value of Dingle temperature and natural selenium vacancies in our crystal suggest that the observed 3D Dirac semimetal state is an outcome of enhanced strain field and weaker effective spin-orbit coupling.

5 pages, 6 figures, This work has been presented at 8th India Singapore Symposium in Condensed Matter Physics Feb 25-Feb 27, 2015 at Indian Institute of Technology, Kanpur, India

References in corpus (10)

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• Classification of stable three-dimensional Dirac semimetals with nontrivial topology
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Cited by in corpus (8)

• Experimental observation of hidden Berry curvature in inversion-symmetric bulk 2H-WSe2
• Topo-fermiology
• Chiral anomaly in Dirac semimetals due to dislocations
• Observation of multichannel quantum coherent transport and electron-electron interaction in Bi2Te3 single crystal
• Schwinger pair creation in Dirac semimetals in the presence of external magnetic and electric fields
• Large linear magnetoresistance and evidence of degeneracy lifting of valence bands in rhombohedral phase of topological crystalline insulator SnTe
• Bulk Rashba spin splitting and Dirac surface state in $p$-type (Bi${}_{0.9}$Sb${}_{0.1}{)}_2$Se${}_3$ single crystal
• Is it possible to determine unambiguously the Berry phase solely from quantum oscillations?