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- Title
Bandgap opening in few-layered monoclinic MoTe<sub>2</sub>.
- Authors
Keum, Dong Hoon; Cho, Suyeon; Kim, Jung Ho; Choe, Duk-Hyun; Sung, Ha-Jun; Kan, Min; Kang, Haeyong; Hwang, Jae-Yeol; Kim, Sung Wng; Yang, Heejun; Chang, K. J.; Lee, Young Hee
- Abstract
Layered transition metal dichalcogenides (TMDs) have attracted renewed interest owing to their potential use as two-dimensional components in next-generation devices. Although group 6 TMDs, such as MX2 with M = (Mo, W) and X = (S, Se, Te), can exist in several polymorphs, most studies have been conducted with the semiconducting hexagonal (2H) phase as other polymorphs often exhibit inhomogeneous formation. Here, we report a reversible structural phase transition between the hexagonal and stable monoclinic (distorted octahedral or 1T′) phases in bulk single-crystalline MoTe2. Furthermore, an electronic phase transition from semimetallic to semiconducting is shown as 1T′-MoTe2 crystals go from bulk to few-layered. Bulk 1T′-MoTe2 crystals exhibit a maximum carrier mobility of 4,000 cm2 V−1 s−1 and a giant magnetoresistance of 16,000% in a magnetic field of 14 T at 1.8 K. In the few-layered form, 1T′-MoTe2 exhibits a bandgap opening of up to 60 meV, which our density functional theory calculations identify as arising from strong interband spin-orbit coupling. We further clarify that the Peierls distortion is a key mechanism to stabilize the monoclinic structure. This class of semiconducting MoTe2 unlocks the possibility of topological quantum devices based on non-trivial Z2-band-topology quantum spin Hall insulators in monoclinic TMDs (ref. ).
- Subjects
SPIN-orbit interactions; BAND gaps; TWO-dimensional models; HEXAGONAL crystal system; MONOCLINIC crystal system; PHASE transitions
- Publication
Nature Physics, 2015, Vol 11, Issue 6, p482
- ISSN
1745-2473
- Publication type
Article
- DOI
10.1038/nphys3314