3,197
Views
4
CrossRef citations to date
0
Altmetric
Reviews

Spectroscopic photoemission and low-energy electron microscopy studies of the surface and electronic structure of two-dimensional materials

&
Article: 1688187 | Received 20 Apr 2019, Accepted 23 Oct 2019, Published online: 10 Dec 2019

References

  • Novoselov KS, Geim AK, Morozov SV, et al. Electric field effect in atomically thin carbon films. Science. 2004;306:1023–1054.
  • Novoselov KS, Geim AK, Morozov S, et al. Two-dimensional gas of massless Dirac fermions in graphene. Nature. 2005;438:197.
  • Zhang Y, Tan Y-W, Stormer HL, et al. Experimental observation of the quantum Hall effect and Berry’s phase in graphene. Nature. 2005;438:201.
  • Geim AK, Novoselov KS. The rise of graphene. Nature Mater 2007;6:183–191. doi:10.1038/nmat1849.
  • Mas-Balleste R, Gomez-Navarro C, Gomez-Herrero J, et al. 2D materials: to graphene and beyond. Nanoscale. 2011;3:20–30.
  • Butler SZ, Hollen SM, Cao L, et al. Progress, challenges, and opportunities in two- dimensional materials beyond graphene. ACS Nano. 2013;7:2898–2926.
  • Bhimanapati GR, Lin Z, Meunier V, et al. Recent advances in two-dimensional materials beyond graphene. ACS Nano. 2015;9:11509–11539.
  • Gupta A, Sakthivel T, Seal S. Recent development in 2D materials beyond graphene. Pro Mater Sci. 2015;73:44–126.
  • Das S, Robinson JA, Dubey M, et al. Beyond graphene: progress in novel two-dimensional materials and van der Waals solids. Annu Rev Mater Res. 2015;45:1–27.
  • Castellanos-Gomez A. Why all the fuss about 2D semiconductors? Nat Photonics. 2016;10:202.
  • Mak KF, Lee C, Hone J, et al. Atomically thin MoS2: a new direct-gap semiconductor. Phys Rev Lett. 2010;105:136805.
  • Splendiani A, Sun L, Zhang Y, et al. Emerging photoluminescence in monolayer MoS2. Nano Lett. 2010;10:1271–1275.
  • Chenet DA, Aslan OB, Huang PY, et al. In-plane anisotropy in mono-and few-layer ReS2 probed by Raman spectroscopy and scanning transmission electron microscopy. Nano Lett. 2015;15:5667–5672.
  • Xi X, Zhao L, Wang Z, et al. Strongly enhanced charge-density-wave order in monolayer NbSe2. Nat Nanotechnol. 2015;10:765.
  • Song L, Ci L, Lu H, et al. Large scale growth and characterization of atomic hexagonal boron nitride layers. Nano Lett. 2010;10:3209–3215.
  • Li L, Yu Y, Ye GJ, et al. Black phosphorus field-effect transistors. Nat Nanotechnol. 2014;9:372.
  • Xia F, Wang H, Jia Y. Rediscovering black phosphorus as an anisotropic layered material for optoelectronics and electronics. Nat Commun. 2014;5:4458.
  • Qiao J, Kong X, Hu Z-X, et al. High-mobility transport anisotropy and linear dichroism in few-layer black phosphorus. Nat Commun. 2014;5:4475.
  • Liu H, Neal AT, Zhu Z, et al. Phosphorene: an unexplored 2D semiconductor with a high hole mobility. ACS Nano. 2014;8:4033–4041.
  • Liu H, Du Y, Deng Y, et al. Semiconducting black phosphorus: synthesis, transport properties and electronic applications. Chem Soc Rev. 2015;44:2732–2743.
  • Zhao Y, Chen Y, Zhang Y-H, et al. Recent advance in black phosphorus: properties and applications. Mater Chem Phys. 2017;189:215–229.
  • Mele EJ. Commensuration and interlayer coherence in twisted bilayer graphene. Phys Rev B. 2010;81:161405.
  • van der Zande AM, Kunstmann J, Chernikov A, et al. Tailoring the electronic structure in bilayer molybdenum disulfide via interlayer twist. Nano Lett. 2014;14:3869–3875.
  • Geim AK, Grigorieva IV. Van der Waals heterostructures. Nature. 2013;499:419.
  • Novoselov K, Mishchenko A, Carvalho A, et al. 2D materials and van der Waals heterostructures. Science. 2016;353:aac9439.
  • Liu Y, Weiss NO, Duan X, et al. Van der Waals heterostructures and devices. Nat Rev Mater. 2016;1:16042.
  • Song JC, Gabor NM. Electron quantum metamaterials in van der Waals heterostructures. Nat Nanotechnol. 2018;13:986.
  • Jin C, Ma EY, Karni O, et al. Ultrafast dynamics in van der Waals heterostructures. Nat Nanotechnol. 2018;13:994.
  • Balendhran S, Walia S, Nili H, et al. Elemental analogues of graphene: silicene, germanene, stanene, and phosphorene. small. 2015;11:640–652.
  • Mannix AJ, Kiraly B, Hersam MC, et al. Synthesis and chemistry of elemental 2D materials. Nat Rev Chem. 2017;1:0014.
  • Ding W, Zhu J, Wang Z, et al. Prediction of intrinsic two-dimensional ferroelectrics in In2Se3 and other III 2-VI 3 van der Waals materials. Nat Commun. 2017;8:14956.
  • Wu M, Jena P. The rise of two-dimensional van der Waals ferroelectrics. Wiley Interdiscip Rev Comput Mol Sci. 2018;8:e1365. doi:10.1002/wcms.1365.
  • Burch KS, Mandrus D, Park J-G. Magnetism in two-dimensional van der Waals materials. Nature. 2018;563:47.
  • Chang K, Liu J, Lin H, et al. Discovery of robust in-plane ferroelectricity in atomic-thick SnTe. Science. 2016;353:274–278.
  • Rinaldi C, Varotto S, Asa M, et al. Ferroelectric control of the spin texture in GeTe. Nano Lett. 2018;18:2751–2758.
  • Du K-Z, Wang X-Z, Liu Y, et al. Weak van der Waals stacking, wide-range band gap, and Raman study on ultrathin layers of metal phosphorus trichalcogenides. ACS Nano. 1738–1743;10:2015.
  • Lee J-U, Lee S, Ryoo JH, et al. Ising-type magnetic ordering in atomically thin FePS3. Nano Lett. 2016;16:7433–7438.
  • Wang X, Du K, Liu YYF, et al. Raman spectroscopy of atomically thin two-dimensional magnetic iron phosphorus trisulfide (FePS3) crystals. 2d Mater. 2016;3:031009.
  • Kuo C-T, Neumann M, Balamurugan K, et al. Exfoliation and Raman spectroscopic fingerprint of few-layer NiPS3 van der Waals crystals. Sci Rep. 2016;6:20904.
  • Tian Y, Gray MJ, Ji H, et al. Magneto-elastic coupling in a potential ferromagnetic 2D atomic crystal. 2d Mater. 2016;3:025035.
  • Huang B, Clark G, Navarro-Moratalla E, et al. Layer-dependent ferromagnetism in a van der Waals crystal down to the monolayer limit. Nature. 2017;546:270.
  • Gong C, Li L, Li Z, et al. Discovery of intrinsic ferromagnetism in two-dimensional van der Waals crystals. Nature. 2017;546:265.
  • Deng Y, Yu Y, Song Y, et al. Gate-tunable room-temperature ferromagnetism in two-dimensional Fe3GeTe2. Nature. 2018;563:94.
  • Damascelli A, Hussain Z, Shen Z-X. Angle-resolved photoemission studies of the cuprate superconductors. Rev Mod Phys. 2003;75:473.
  • Lu D, Vishik IM, Yi M, et al. Angle-resolved photoemission studies of quantum materials. Annu Rev Condens Matter Phys. 2012;3:129–167.
  • Vishik I. Photoemission perspective on pseudogap, superconducting fluctuations, and charge order in cuprates: a review of recent progress. Rep Prog Phys. 2018;81:062501.
  • Obraztsov AN. Chemical vapour deposition: making graphene on a large scale. Nat Nanotechnol. 2009;4:212.
  • van der Zande AM, Huang PY, Chenet DA, et al. Grains and grain boundaries in highly crystalline monolayer molybdenum disulphide. Nat Mater. 2013;12:554.
  • Zhang Y, Chang T-R, Zhou B, et al. Direct observation of the transition from indirect to direct bandgap in atomically thin epitaxial MoSe2. Nat Nanotechnol. 2014;9:111–115.
  • Bauer E, Mundschau M, Swiech W, et al. Surface studies by low-energy electron microscopy (LEEM) and conventional UV photoemission electron microscopy (PEEM). Ultramicroscopy. 1989;31:49–57.
  • Schmidt T, Heun S, Slezak J, et al. SPELEEM: combining LEEM and spectroscopic imaging. Surf Rev Lett. 1998;5:1287–1296.
  • Locatelli A, Bianco A, Cocco D, et al.. High lateral resolution spectroscopic imaging of surfaces: the undulator beamline Nanospectroscopy at Elettra. In: Journal de Physique IV (Proceedings);EDP sciences; 2003;104:99–102. doi:10.1051/jp4:200300038.
  • Locatelli A, Aballe L, Mentes T, et al. Photoemission electron microscopy with chemical sensitivity: SPELEEM methods and applications. Surf Interface Anal. 2006;38:1554–1557.
  • Bauer E. Cathode lens electron microscopy: past and future. J Phys. 2009;21:314001.
  • Mentes TO, Niño MA, Locatelli A. Spectromicroscopy with low-energy electrons: LEEM and XPEEM studies at the nanoscale. e-J Surf Sci Nanotechnol. 2011;9:72–79.
  • Menteş TO, Locatelli A. Angle-resolved X-ray photoemission electron microscopy. J Electron Spectros Relat Phenomena. 2012;185:323–329.
  • Palomino RM, Stavitski E, Waluyo I, et al. New in-situ and operando facilities for catalysis science at NSLS-II: the deployment of real-time, chemical, and structure- sensitive x-ray probes. Synchrotron Radiat News. 2017;30:30–37.
  • Amati M, Barinov A, Feyer V, et al. Photoelectron microscopy at Elettra: recent advances and perspectives. J Electron Spectros Relat Phenomena. 2018;224:59–67.
  • Liu H, Zhang G, Richard P, et al. Spatially resolved x-ray photoemission electron microscopy of Weyl semimetal NbAs. Cryst Growth Des. 2018;18:5210–5213.
  • Yeh P-C, Jin W, Zaki N, et al. Layer-dependent electronic structure of an atomically heavy two-dimensional dichalcogenide. Phys Rev B. 2015;91:041407.
  • Mo S-K. Angle-resolved photoemission spectroscopy for the study of two-dimensional materials. Nano Convergence. 2017;4:6.
  • Yang H, Liang A, Chen C, et al. Visualizing electronic structures of quantum materials by angle-resolved photoemission spectroscopy. Nat Rev Mater. 2018;3:341.
  • Cattelan M, Fox N. A perspective on the application of spatially resolved ARPES for 2D materials. Nanomaterials. 2018;8:284.
  • Dudin P, Lacovig P, Fava C, et al. Angle-resolved photoemission spectroscopy and imaging with a submicrometre probe at the SPECTROMICROSCOPY-3.2 L beamline of Elettra. J Synchrotron Radiat. 2010;17:445–450.
  • Avila J, Asensio MC. First nanoARPES user facility available at SOLEIL: an innovative and powerful tool for studying advanced materials. Synchrotron Radiat News. 2014;27:24–30.
  • Avila J, Boury A, Caja-Muñoz B, et al.. Optimal focusing system of the fresnel zone plates at the synchrotron SOLEIL NanoARPES beamline. In: Journal of physics: conference series; IOP Publishing; 2017. Vol. 849, p. 012039. doi:10.1088/1742-6596/849/1/012039.
  • Usachov D, Vilkov O, Gruneis A, et al. Nitrogen-doped graphene: efficient growth, structure, and electronic properties. Nano Lett. 2011;11:5401–5407.
  • Schneider C, Wiemann C, Patt M, et al. Expanding the view into complex material systems: from micro-ARPES to nanoscale HAXPES. J Electron Spectros Relat Phenomena. 2012;185:330–339.
  • Barrett N, Conrad E, Winkler K, et al. Dark field photoelectron emission microscopy of micron scale few layer graphene. Rev Sci Instrum. 2012;83:083706.
  • Cattelan M, Agnoli S, Favaro M, et al. Microscopic view on a chemical vapor deposition route to boron-doped graphene nanostructures. Chem Mater. 2013;25:1490–1495.
  • Cattelan M, Peng G, Cavaliere E, et al. The nature of the Fe–graphene interface at the nanometer level. Nanoscale. 2015;7:2450–2460.
  • Le D, Barinov A, Preciado E, et al. Spin–orbit coupling in the band structure of monolayer WSe2. J Phys. 2015;27:182201.
  • Arango YC, Huang L, Chen C, et al. Quantum transport and nano angle-resolved photoemission spectroscopy on the topological surface states of single Sb2Te3 nanowires. Sci Rep. 2016;6:29493.
  • Hart LS, Webb JL, Dale S, et al. Electronic bandstructure and van der waals coupling of ReSe2 revealed by high-resolution angle-resolved photoemission spectroscopy. Sci Rep. 2017;7:5145.
  • Agnoli S, Ambrosetti A, Mentes TO, et al. Unraveling the structural and electronic properties at the WSe2–graphene interface for a rational design of van der Waals heterostructures. ACS Appl Nano Mater. 2018;1:1131–1140.
  • Escher M, Weber N, Merkel M, et al. NanoESCA: a novel energy filter for imaging x-ray photoemission spectroscopy. J Phys. 2005;17:S1329.
  • Gehlmann M, Aguilera I, Bihlmayer G, et al. Direct observation of the band gap transition in atomically thin ReS2. Nano Lett. 2017;17:5187–5192.
  • Adams DL. A simple and effective procedure for the refinement of surface structure in LEED. Surf Sci. 2002;519:157–172.
  • Pendry JB. Low energy electron diffraction. London: Academic Press; 1974.
  • Van Hove MA, Tong SY. Surface crystallography by LEED: theory, computation and structural results. Vol. 2. Springer Science & Business Media; 2012. doi:10.1007/978-3-642-67195-1.
  • Ferrari AC. Raman spectroscopy of graphene and graphite: disorder, electron–phonon coupling, doping and nonadiabatic effects. Solid State Commun. 2007;143:47–57.
  • Malard L, Pimenta M, Dresselhaus G, et al. Raman spectroscopy in graphene. Phys Rep. 2009;473:51–87.
  • Ferrari AC, Basko DM. Raman spectroscopy as a versatile tool for studying the properties of graphene. Nat Nanotechnol. 2013;8:235.
  • Lee C, Yan H, Brus LE, et al. Anomalous lattice vibrations of single-and few-layer MoS2. ACS Nano. 2010;4:2695–2700.
  • Li H, Zhang Q, Yap CCR, et al. From bulk to monolayer MoS2: evolution of Raman scattering. Adv Funct Mater. 2012;22:1385–1390.
  • Sutter P, Sadowski JT, Sutter E. Graphene on Pt (111): growth and substrate interaction. Phys Rev B. 2009;80:245411.
  • Sutter P, Sutter E. Microscopy of graphene growth, processing, and properties. Adv Funct Mater. 2013;23:2617–2634.
  • Hao Y, Bharathi M, Wang L, et al. The role of surface oxygen in the growth of large single-crystal graphene on copper. Science. 2013;1243879:720–723. doi:10.1126/science.1243879.
  • Hibino H, Kageshima H, Maeda F, et al. Thickness determination of graphene layers formed on SiC using low-energy electron microscopy. e-J Surf Sci Nanotechnol. 2008;6:107–110.
  • Forti S, Emtsev K, Coletti C, et al. Large-area homogeneous quasifree standing epitaxial graphene on SiC (0001): electronic and structural characterization. Phys Rev B. 2011;84:125449.
  • Emtsev KV, Zakharov AA, Coletti C, et al. Ambipolar doping in quasifree epitaxial graphene on SiC (0001) controlled by Ge intercalation. Phys Rev B. 2011;84:125423.
  • Ohta T, Beechem TE, Robinson JT, et al. Long-range atomic ordering and variable interlayer interactions in two overlapping graphene lattices with stacking misorientations. Phys Rev B. 2012;85:075415.
  • Feenstra RM, Srivastava N, Gao Q, et al. Low-energy electron reflectivity from graphene. Phys Rev B. 2013;87:041406.
  • Srivastava N, Gao Q, Widom M, et al. Low-energy electron reflectivity of graphene on copper and other substrates. Phys Rev B. 2013;87:245414.
  • Jobst J, Kautz J, Geelen D, et al. Nanoscale measurements of unoccupied band dispersion in few-layer graphene. Nat Commun. 2015;6:8926.
  • Fasolino A, Los J, Katsnelson MI. Intrinsic ripples in graphene. Nat Mater. 2007;6:858.
  • Guinea F, Horovitz B, Le Doussal P. Gauge field induced by ripples in graphene. Phys Rev B. 2008;77:205421.
  • Lui CH, Liu L, Mak KF, et al. Ultraflat graphene. Nature. 2009;462:339.
  • Knox KR, Wang S, Morgante A, et al. Spectromicroscopy of single and multilayer graphene supported by a weakly interacting substrate. Phys Rev B. 2008;78:201408.
  • Locatelli A, Knox KR, Cvetko D, et al. Corrugation in exfoliated graphene: an electron microscopy and diffraction study. ACS Nano. 2010;4:4879–4889.
  • Dai Z, Jin W, Grady M, et al. Surface structure of bulk 2H-MoS2 (0001) and exfoliated suspended monolayer MoS2: A selected area low energy electron diffraction study. Surf Sci. 2017;660:16–21.
  • Dai Z, Jin W, Yu J-X, et al. Surface buckling of black phosphorus: determination, origin, and influence on electronic structure. Phys Rev Mater. 2017;1:074003.
  • Zhang C, Lian J, Yi W, et al. Surface structures of black phosphorus investigated with scanning tunneling microscopy. J Phys Chem C. 2009;113:18823–18826.
  • Liang L, Wang J, Lin W, et al. Electronic bandgap and edge reconstruction in phosphorene materials. Nano Lett. 2014;14:6400–6406.
  • Fu L. Topological crystalline insulators. Phys Rev Lett. 2011;106:106802.
  • Hsieh TH, Lin H, Liu J, et al. Topological crystalline insulators in the SnTe material class. Nat Commun. 2012;3:982.
  • Littlewood P, Mihaila B, Schulze R, et al. Band structure of SnTe studied by photoemission spectroscopy. Phys Rev Lett. 2010;105:086404.
  • Tanaka Y, Ren Z, Sato T, et al. Experimental realization of a topological crystalline insulator in SnTe. Nat Phys. 2012;8:800.
  • Dziawa P, Kowalski B, Dybko K, et al. Topological crystalline insulator states in Pb1–xSnxSe. Nat Mater. 2012;11:1023.
  • Xu S-Y, Liu C, Alidoust N, et al. Observation of a topological crystalline insulator phase and topological phase transition in Pb1–xSnxTe. Nat Commun. 2012;3:1192.
  • Zhang Y, Liu Z, Zhou B, et al. ARPES study of the epitaxially grown topological crystalline insulator SnTe (111). J Electron Spectros Relat Phenomena. 2017;219:35–40.
  • Jin W, Vishwanath S, Liu J, et al. Electronic structure of the metastable epitaxial rock-salt snse {111} topological crystalline insulator. Phys Rev X. 2017;7:041020.
  • Jin W, Yeh P-C, Zaki N, et al. Tuning the electronic structure of monolayer graphene/MoS2 van der Waals heterostructures via interlayer twist. Phys Rev B. 2015;92:201409.
  • Xiao D, Liu G-B, Feng W, et al. Coupled spin and valley physics in mono- layers of MoS2 and other group-VI dichalcogenides. Phys Rev Lett. 2012;108:196802.
  • Jin W, Yeh P-C, Zaki N, et al. Direct measurement of the thickness-dependent electronic band structure of MoS2 using angle- resolved photoemission spectroscopy. Phys Rev Lett. 2013;111:106801.
  • Zhang P, Richard P, Qian T, et al. A precise method for visualizing dispersive features in image plots. Rev Sci Instrum. 2011;82:043712.
  • Ali MN, Xiong J, Flynn S, et al. Large, non-saturating magnetoresistance in WTe2. Nature. 2014;514:205.
  • Thoutam L, Wang Y, Xiao Z, et al. Temperature-dependent three-dimensional anisotropy of the magnetoresistance in WTe2. Phys Rev Lett. 2015;115:046602.
  • Soluyanov AA, Gresch D, Wang Z, et al. Type-II Weyl semimetals. Nature. 2015;527:495.
  • Sun Y, Wu S-C, Ali MN, et al. Prediction of Weyl semimetal in orthorhombic MoTe2. Phys Rev B. 2015;92:161107.
  • Wang Z, Gresch D, Soluyanov AA, et al. MoTe2: a type-II Weyl topological metal. Phys Rev Lett. 2016;117:056805.
  • Sánchez-Barriga J, Vergniory M, Evtushinsky D, et al. Surface fermi arc connectivity in the type-ii weyl semimetal candidate WTe2. Phys Rev B. 2016;94:161401.
  • Bruno FY, Tamai A, Wu Q, et al. Observation of large topologically trivial fermi arcs in the candidate type-ii weyl semimetal WTe2. Phys Rev B. 2016;94:121112.
  • Wang C, Zhang Y, Huang J, et al. Observation of fermi arc and its connection with bulk states in the candidate type-ii weyl semimetal WTe2. Phys Rev B. 2016;94:241119.
  • Deng K, Wan G, Deng P, et al. Experimental observation of topological fermi arcs in type-ii weyl semimetal MoTe2. Nat Phys. 2016;12:1105–1110.
  • Huang L, McCormick TM, Ochi M, et al. Spectroscopic evidence for a type ii weyl semimetallic state in MoTe2. Nat Mater. 2016;15:1155–1160.
  • Tamai A, Wu QS, Cucchi I, et al. Fermi arcs and their topological character in the candidate type-ii weyl semimetal mote2. Phys Rev X. 2016;6:031021.
  • Jiang J, Liu Z, Sun Y, et al. Signature of type-ii weyl semimetal phase in MoTe2. Nat Commun. 2017;8:13973.
  • Jin W, Schiros T, Lin Y, et al. Phase transition and electronic structure evolution of MoTe2 induced by w substitution. Phys Rev B. 2018;98:144114.
  • Qian X, Liu J, Fu L, et al. Quantum spin Hall effect in two-dimensional transition metal dichalcogenides. Science. 2014;346:1344–1347.
  • Arguello C, Rosenthal EP, Andrade EF, et al. Quasiparticle interference, quasiparticle interactions, and the origin of the charge density wave in 2h-NbSe2. Phys Rev Lett. 2015;114:037001.
  • Xi X, Wang Z, Zhao W, et al. Ising pairing in superconducting NbSe2 atomic layers. Nat Phys. 2016;12:139.
  • Ugeda MM, Bradley AJ, Zhang Y, et al. Characterization of collective ground states in single-layer NbSe2. Nat Phys. 2016;12:92.
  • Sanders CE, Dendzik M, Ngankeu AS, et al. Crystalline and electronic structure of single-layer TaS2. Phys Rev B. 2016;94:081404.
  • Chen P, Chan Y-H, Wong M-H, et al. Dimensional effects on the charge density waves in ultrathin films of TiSe2. Nano Lett. 2016;16:6331–6336.
  • Chen P, Chan Y-H, Fang X-Y, et al. Hidden order and dimensional crossover of the charge density waves in TiSe2. Sci Rep. 2016;6:37910.
  • Kolekar S, Bonilla M, Ma Y, et al. Layer-and substrate-dependent charge density wave criticality in 1t–tiSe2. 2d Mater. 2017;5:015006.
  • Kolekar S, Bonilla M, Diaz HC, et al. Controlling the charge density wave transition in monolayer TiSe2: substrate and doping effects. Adv Quantum Technol. 2018;1:1800070.
  • Umemoto Y, Sugawara K, Nakata Y, et al. Pseudogap, fermi arc, and peierls-insulating phase induced by 3d–2d crossover in monolayer VSe2. Nano Res. 2018. DOI:10.1007/s12274-018-2196-4
  • Feng J, Biswas D, Rajan A, et al. Electronic structure and enhanced charge- density wave order of monolayer VSe2. Nano Lett. 2018;18:4493–4499.
  • Duvjir G, Choi BK, Jang I, et al. Emergence of a metal–insulator transition and high-temperature charge- density waves in VSe2 at the monolayer limit. Nano Lett. 2018;18:5432–5438.
  • Bonilla M, Kolekar S, Ma Y, et al. Strong room-temperature ferromagnetism in VSe2 monolayers on van der Waals substrates. Nat Nanotechnol. 2018;13:289.
  • Zhou SY, Gweon G-H, Fedorov A, et al. Substrate-induced bandgap opening in epitaxial graphene. Nat Mater. 2007;6:770.
  • Knox KR, Locatelli A, Yilmaz MB, et al. Making angle-resolved photoemission measurements on corrugated monolayer crystals: suspended exfoliated single-crystal graphene. Phys Rev B. 2011;84:115401.
  • Jin W, Yeh P-C, Zaki N, et al. Substrate interactions with suspended and supported monolayer MoS2: angle-resolved photoemission spectroscopy. Phys Rev B. 2015;91:121409.
  • Rivera P, Schaibley JR, Jones AM, et al. Observation of long-lived interlayer excitons in monolayer MoSe2–wSe2 heterostructures. Nat Commun. 2015;6:6242.
  • Chen H, Wen X, Zhang J, et al. Ultrafast formation of interlayer hot excitons in atomically thin MoS2/WS2 heterostructures. Nat Commun. 2016;7:12512.
  • Mak KF, Shan J. Opportunities and challenges of interlayer exciton control and manipulation. Nat Nanotechnol. 2018;13:974.
  • Coy Diaz H, Avila J, Chen C, et al. Direct observation of interlayer hybridization and dirac relativistic carriers in graphene/MoS2 van der waals heterostructures. Nano Lett. 2015;15:1135–1140.
  • Katoch J, Ulstrup S, Koch RJ, et al. Giant spin-splitting and gap renormalization driven by trions in single-layer WS2/h-BN heterostructures. Nat Phys. 2018;14:355.
  • Wilson NR, Nguyen PV, Seyler K, et al. Determination of band offsets, hybridization, and exciton binding in 2d semiconductor heterostructures. Sci Adv. 2017;3:e1601832.
  • Dau MT, Gay M, Di Felice D, et al. Beyond van der Waals interaction: the case of MoSe2 epitaxially grown on few-layer graphene. ACS Nano. 2018;12:2319–2331.
  • Soavi G, De Fazio D, Tamalampudi S, D. Yoon, E. Mostaani, A. R. Botello, S. D. Conte, G. Cerullo, I. Goykhman, and A. C. Ferrari, "Gate tuneable ultrafast charge transfer in graphene/MoS2 heterostructures," in 2017 European Conference on Lasers and Electro-Optics and European Quantum Electronics Conference, (Optical Society of America, 2017), paper EI_4_2, Munich, Germany. doi:10.1109/CLEOE-EQEC.2017.8087707.
  • Liao M, Wu Z-W, Du L, et al. Twist angle-dependent conductivities across MoS2/graphene heterojunctions. Nat Commun. 2018;9:4068.
  • Yeh P-C, Jin W, Zaki N, et al. Direct measurement of the tunable electronic structure of bilayer MoS2 by interlayer twist. Nano Lett. 2016;16:953–959.
  • Bistritzer R, MacDonald AH. Moiré bands in twisted double-layer graphene. Proc Nat Acad Sci. 2011;108:12233–12237.
  • Tong Q, Yu H, Zhu Q, et al. Topological mosaics in moiré superlattices of van der Waals heterobilayers. Nat Phys. 2017;13:356.
  • Kim K, DaSilva A, Huang S, et al. Tunable moiré bands and strong correlations in small-twist-angle bilayer graphene. Proc Nat Acad Sci. 2017;114:3364–3369.
  • Chittari BL, Chen G, Zhang Y, et al. Gate-tunable topological flat bands in trilayer graphene boron-nitride moiré superlattices. Phys Rev Lett. 2019;122:016401.
  • Yankowitz M, Xue J, Cormode D, et al. Emergence of superlattice Dirac points in graphene on hexagonal boron nitride. Nat Phys. 2012;8:382.
  • Ponomarenko L, Gorbachev R, Yu G, et al. Cloning of Dirac fermions in graphene superlattices. Nature. 2013;497:594.
  • Hunt B, Sanchez-Yamagishi J, Young A, et al. Massive Dirac fermions and Hofstadter butterfly in a van der waals heterostructure. Science. 2013;340:1427–1430.
  • Dean CR, Wang L, Maher P, et al. Hofstadter?s butterfly and the fractal quantum hall effect in moiré superlattices. Nature. 2013;497:598.
  • Cao Y, Fatemi V, Fang S, et al. Unconventional superconductivity in magic-angle graphene superlattices. Nature. 2018;556:43.
  • Cao Y, Fatemi V, Demir A, et al. Correlated insulator behaviour at half-filling in magic-angle graphene superlattices. Nature. 2018;556:80.
  • Yu H, Liu G-B, Tang J, et al. Moiré excitons: from programmable quantum emitter arrays to spin-orbit–coupled artificial lattices. Sci Adv. 2017;3:e1701696.
  • Zhang N, Surrente A, Baranowski M, et al. Moiré intralayer excitons in a MoSe2/MoS2 heterostructure. Nano Lett. 2018;18:7651–7657.
  • Jin C, Regan EC, Yan A, et al. Observation of moiré excitons in WSe2/WS2 heterostructure superlattices. Nature. 2019;567:76–80.. doi:10.1038/s41586-019-0976-y.
  • Tran K, Moody G, Wu F, et al. Evidence for moiré excitons in van der Waals heterostructures. Nature. 2019;567:71–75. doi:10.1038/s41586-019-0975-z.
  • Alexeev EM, Ruiz-Tijerina DA, Danovich M, et al. Resonantly hybridized excitons in moiré superlattices in van der Waals heterostructures. Nature. 2019;567:81.
  • Seyler KL, Rivera P, Yu H, et al. Signatures of moiré-trapped valley excitons in MoSe2/WSe2 heterobilayers. Nature. 2019;567:66–70. doi:10.1038/s41586-019-0957-1.
  • Carr S, Massatt D, Fang S, et al. Twistronics: manipulating the electronic properties of two-dimensional layered structures through their twist angle. Phys Rev B. 2017;95:075420.
  • Batzill M. The surface science of graphene: metal interfaces, CVD synthesis, nanoribbons, chemical modifications, and defects. Surf Sci Rep. 2012;67:83–115.
  • Sutter P, Hybertsen M, Sadowski J, et al. Electronic structure of few-layer epitaxial graphene on Ru (0001). Nano Lett. 2009;9:2654–2660.
  • Keyshar K, Berg M, Zhang X, et al. Experimental determination of the ionization energies of MoSe2, WS2, and MoS2 on SiO2 using photoemission electron microscopy. ACS Nano. 2017;11:8223–8230.
  • Berg M, Keyshar K, Bilgin I, et al. Layer dependence of the electronic band alignment of few-layer MoS2 on SiO2 measured using photoemission electron microscopy. Phys Rev B. 2017;95:235406.
  • Menteş T, Zamborlini G, Sala A, et al. Cathode lens spectromicroscopy: methodology and applications. Beilstein J Nanotechnol. 1873–1886;5:2014.
  • Xia C, Watcharinyanon S, Zakharov A, et al. Si intercalation/deintercalation of graphene on 6h-SiC (0001). Phys Rev B. 2012;85:045418.
  • Locatelli A, Wang C, Africh C, et al. Temperature-driven reversible rippling and bonding of a graphene superlattice. ACS Nano. 2013;7:6955–6963.
  • Locatelli A, Zamborlini G, Menteş TO. Growth of single and multi-layer graphene on Ir (100). Carbon. 2014;74:237–248.
  • Mahatha S, Moras P, Sheverdyaeva P, et al. Absence of dirac cones in monolayer silicene and multilayer Si films on Ag (111). J Electron Spectros Relat Phenomena. 2017;219:2–8.
  • Fortin-Deschênes M, Waller O, Mentes T, et al. Synthesis of antimonene on germanium. Nano Lett. 2017;17:4970–4975.
  • Riley JM, Mazzola F, Dendzik M, et al. Direct observation of spin-polarized bulk bands in an inversion-symmetric semiconductor. Nat Phys. 2014;10:835.
  • Mo S-K, Hwang C, Zhang Y, et al. Spin-resolved photoemission study of epitaxially grown MoSe2 and WSe2 thin films. J Phys. 2016;28:454001.
  • Jin W, Kim HH, Ye Z, et al. Raman fingerprint of two terahertz spin wave branches in a two-dimensional honeycomb ising ferromagnet. Nat Commun. 2018;9:5122.
  • Thiel L, Wang Z, Tschudin MA, et al. Probing magnetism in 2D materials at the nanoscale with single-spin microscopy. Science. 2019;364:973–976.
  • van der Laan G, Thole B. Strong magnetic x-ray dichroism in 2p absorption spectra of 3d transition-metal ions. Phys Rev B. 1991;43:13401.
  • Stöhr J. Exploring the microscopic origin of magnetic anisotropies with x-ray magnetic circular dichroism (XMCD) spectroscopy. J Magn Magn Mater. 1999;200:470–497.
  • Locatelli A, Cherifi S, Heun S, et al. X-ray magnetic circular dichroism imaging in a low energy electron microscope. Surf Rev Lett. 2002;9:171–176.
  • Li Q, Yang M, Gong C, et al. Patterning-induced ferromagnetism of Fe3GeTe2 van der waals materials beyond room temperature. Nano Lett. 2018;18:5974–5980.
  • Bayer D, Wiemann C, Gaier O, et al. Time-resolved 2PPE and time-resolved PEEM as a probe of LSP’s in silver nanoparticles. J Nanomater. 2008;2008:11. doi:org/10.1155/2008/249514.
  • Aeschlimann M, Bauer M, Bayer D, et al. Spatiotemporal control of nanooptical excitations. Proc Nat Acad Sci. 2010;107:5329–5333.
  • Fukumoto K, Yamada Y, Onda K, et al. Direct imaging of electron re- combination and transport on a semiconductor surface by femtosecond time-resolved photoemission electron microscopy. Appl Phys Lett. 2014;104:053117.
  • Fukumoto K, Onda K, Yamada Y, et al. Femtosecond time-resolved photoemission electron microscopy for spatiotemporal imaging of photogenerated carrier dynamics in semiconductors. Rev Sci Instrum. 2014;85:083705.
  • Man MK, Margiolakis A, Deckoff-Jones S, et al. Imaging the motion of electrons across semiconductor heterojunctions. Nat Nanotechnol. 2017;12:36.
  • Wong EL, Winchester AJ, Pareek V, et al. Pulling apart photoexcited electrons by photoinducing an in-plane surface electric field. Sci Adv. 2018;4:eaat9722.