Controlling the charge density wave transition in single-layer TiTe2xSe2(1−x) alloys by band gap engineering
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Date
10/01/2024Author
Grant ID
2016-006
URF/R/180026
EP/M023958/1
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Show full item recordAbstract
Closing the band gap of a semiconductor, into a semimetallic state, gives a powerful potential route to tune the electronic energy gains that drive collective phases like charge density waves (CDW) and excitonic insulator states. We explore this approach for the controversial CDW material monolayer (ML) TiSe2 by engineering its narrow band gap to the semimetallic limit of ML-TiTe2. Using molecular beam epitaxy, we demonstrate the growth of ML-TiTe2xSe2(1−x) alloys across the entire compositional range, and unveil how the (2 × 2) CDW instability evolves through the normal state semiconductor-semimetal transition via in situ angle-resolved photoemission spectroscopy. Through model electronic structure calculations, we identify how this tunes the relative strength of excitonic and Peierls-like coupling, demonstrating band gap engineering as a powerful method for controlling the microscopic mechanisms underpinning the formation of collective states in two-dimensional materials.
Citation
Antonelli , T , Rajan , A , Watson , M D , Soltani , S , Houghton , J , Siemann , G-R , Zivanovic , A , Bigi , C , Edwards , B M & King , P 2024 , ' Controlling the charge density wave transition in single-layer TiTe 2x Se 2(1−x) alloys by band gap engineering ' , Nano Letters , vol. 24 , no. 1 , 3c03776 , pp. 215-221 . https://doi.org/10.1021/acs.nanolett.3c03776
Publication
Nano Letters
Status
Peer reviewed
ISSN
1530-6984Type
Journal item
Description
Funding: We gratefully acknowledge support from the Leverhulme Trust via Grant No. RL-2016-006 and the UK Royal Society. The MBE growth facility was funded through an EPSRC strategic equipment grant: EP/M023958/1.Collections
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