@article{53edc4291a1947c492e3e3dd810d6038,
title = "Unique Gap Structure and Symmetry of the Charge Density Wave in Single-Layer VSe2",
abstract = "Single layers of transition metal dichalcogenides (TMDCs) are excellent candidates for electronic applications beyond the graphene platform; many of them exhibit novel properties including charge density waves (CDWs) and magnetic ordering. CDWs in these single layers are generally a planar projection of the corresponding bulk CDWs because of the quasi-two-dimensional nature of TMDCs; a different CDW symmetry is unexpected. We report herein the successful creation of pristine single-layer VSe2, which shows a (7×3) CDW in contrast to the (4×4) CDW for the layers in bulk VSe2. Angle-resolved photoemission spectroscopy from the single layer shows a sizable (7×3) CDW gap of ∼100 meV at the zone boundary, a 220 K CDW transition temperature twice the bulk value, and no ferromagnetic exchange splitting as predicted by theory. This robust CDW with an exotic broken symmetry as the ground state is explained via a first-principles analysis. The results illustrate a unique CDW phenomenon in the two-dimensional limit.",
author = "P. Chen and Pai, {Woei Wu} and Chan, {Y. H.} and V. Madhavan and Chou, {M. Y.} and Mo, {S. K.} and Fedorov, {A. V.} and Chiang, {T. C.}",
note = "Funding Information: This work is supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, Division of Materials Science and Engineering, under Grant No. DE-FG02-07ER46383 (T. C. C.), the National Science Foundation under Grant No. EFMA-1542747 (M. Y. C.), Academia Sinica under Grant No. AS-TP-106-M07 (M. Y. C.), the Ministry of Science and Technology of Taiwan under Grant No. 103-2923-M-002-003-MY3 and the Center of Atomic Initiative for New Materials, National Taiwan University (W. W. P.), and the Gordon and Betty Moore Foundation{\textquoteright}s EPiQS Initiative through Grant No. GBMF4860 (V. M.). The Advanced Light Source is supported by the Director, Office of Science, Office of Basic Energy Sciences, of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231. We thank Alpha T. N{\textquoteright}Diaye for insightful discussions. Publisher Copyright: {\textcopyright} 2018 American Physical Society.",
year = "2018",
month = nov,
day = "9",
doi = "10.1103/PhysRevLett.121.196402",
language = "English (US)",
volume = "121",
journal = "Physical Review Letters",
issn = "0031-9007",
publisher = "American Physical Society",
number = "19",
}