Electronic Structure and Enhanced Charge-Density Wave Order of Monolayer VSe<sub>2</sub> Jiagui Feng Deepnarayan Biswas Akhil Rajan Matthew D. Watson Federico Mazzola Oliver J. Clark Kaycee Underwood Igor Marković Martin McLaren Andrew Hunter David M. Burn Liam B. Duffy Sourabh Barua Geetha Balakrishnan François Bertran Patrick Le Fèvre Timur K. Kim Gerrit van der Laan Thorsten Hesjedal Peter Wahl Phil D. C. King 10.1021/acs.nanolett.8b01649.s001 https://acs.figshare.com/articles/journal_contribution/Electronic_Structure_and_Enhanced_Charge-Density_Wave_Order_of_Monolayer_VSe_sub_2_sub_/6654170 How the interacting electronic states and phases of layered transition-metal dichalcogenides evolve when thinned to the single-layer limit is a key open question in the study of two-dimensional materials. Here, we use angle-resolved photoemission to investigate the electronic structure of monolayer VSe<sub>2</sub> grown on bilayer graphene/SiC. While the global electronic structure is similar to that of bulk VSe<sub>2</sub>, we show that, for the monolayer, pronounced energy gaps develop over the entire Fermi surface with decreasing temperature below <i>T</i><sub>c</sub> = 140 ± 5 K, concomitant with the emergence of charge-order superstructures evident in low-energy electron diffraction. These observations point to a charge-density wave instability in the monolayer that is strongly enhanced over that of the bulk. Moreover, our measurements of both the electronic structure and of X-ray magnetic circular dichroism reveal no signatures of a ferromagnetic ordering, in contrast to the results of a recent experimental study as well as expectations from density functional theory. Our study thus points to a delicate balance that can be realized between competing interacting states and phases in monolayer transition-metal dichalcogenides. 2018-06-18 00:00:00 use angle-resolved photoemission single-layer limit Enhanced Charge-Density Wave Order low-energy electron diffraction monolayer transition-metal dichalcogenides charge-order superstructures transition-metal dichalcogenides observations point energy gaps T c Monolayer VSe 2 Fermi surface phase Electronic Structure monolayer VSe 2 charge-density wave instability bulk VSe 2