Interaction driven many-body phases of optically generated exciton ensembles in van der Waals heterostructures

• Applicants: Professor Dr. Alexander Walter Holleitner; Professorin Dr. Ursula Wurstbauer
• Subject Area: Experimental Condensed Matter Physics
• Term: from 2016 to 2024
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 290642686

• Final Report Year: 2024

Final Report Abstract

The project aimed to investigate the phase diagram and phase transitions of strongly interacting excitonic ensembles in van der Waal's heterostructures at very low temperatures and high exciton densities. In particular, the ground state properties of the individual phases were identified by their specific fingerprint, the low-energy luminescence spectrum. Based on them, various spectroscopic methods including photoluminescence, Raman, photoluminescence excitation (PLE) spectroscopies as well as spectroscopic imaging ellipsometry (SIE) were utilized to test various material combination, twist angles, encapsulation with hexagonal boron nitride and field-effect structures in order to establish suitable van der Waals heterostructures for the main goal of the project. Within the framework of the project, first signatures for degenerate excitonic ensembles were reported, such as a reduction in the luminescence linewidth with an increase in the number of excitons and a corresponding increase in temporal coherence. Moreover, it could be shown for the first time that the luminescence of such excitonic ensembles can be spatially coherent, when the exciton ensembles can be considered to be degenerate.

Publications

• Imaging spectroscopic ellipsometry of MoS2. Journal of Physics: Condensed Matter, 28(38), 385301.
  Funke, S.; Miller, B.; Parzinger, E.; Thiesen, P.; Holleitner, A. W. & Wurstbauer, U.
  
• Collective electronic excitation in a trapped ensemble of photogenerated dipolar excitons and free holes revealed by inelastic light scattering. Physical Review B, 95(8).
  Dietl, Sebastian; Wang, Sheng; Schuh, Dieter; Wegscheider, Werner; Kotthaus, Jörg P.; Pinczuk, Aron; Holleitner, Alexander W. & Wurstbauer, Ursula
  
• Hydrogen evolution activity of individual mono-, bi-, and few-layer MoS 2 towards photocatalysis. Applied Materials Today, 8, 132-140.
  Parzinger, Eric; Mitterreiter, Elmar; Stelzer, Max; Kreupl, Franz; Ager, Joel W.; Holleitner, Alexander W. & Wurstbauer, Ursula
  
• Light–matter interaction in transition metal dichalcogenides and their heterostructures. Journal of Physics D: Applied Physics, 50(17), 173001.
  Wurstbauer, Ursula; Miller, Bastian; Parzinger, Eric & Holleitner, Alexander W.
  
• Long-Lived Direct and Indirect Interlayer Excitons in van der Waals Heterostructures. Nano Letters, 17(9), 5229-5237.
  Miller, Bastian; Steinhoff, Alexander; Pano, Borja; Klein, Julian; Jahnke, Frank; Holleitner, Alexander & Wurstbauer, Ursula
  
• Overflow of a dipolar exciton trap at high magnetic fields. Superlattices and Microstructures, 108, 42-50.
  Dietl, S.; Kowalik-Seidl, K.; Schuh, D.; Wegscheider, W.; Holleitner, A.W. & Wurstbauer, U.
  
• Impact of substrate induced band tail states on the electronic and optical properties of MoS2. Applied Physics Letters, 115(26).
  Klein, J.; Kerelsky, A.; Lorke, M.; Florian, M.; Sigger, F.; Kiemle, J.; Reuter, M. C.; Taniguchi, T.; Watanabe, K.; Finley, J. J.; Pasupathy, A. N.; Holleitner, A. W.; Ross, F. M. & Wurstbauer, U.
  
• On the parabolicity of dipolar exciton traps and their population of excess charge carriers. New Journal of Physics, 21(6), 063028.
  Dietl, S.; Sigl, L.; Sponfeldner, L.; Gardner, G.; Manfra, M.; Kotthaus, J. P.; Wurstbauer, U. & Holleitner, A. W.
  
• Tuning the Fröhlich exciton-phonon scattering in monolayer MoS2. Nature Communications, 10(1).
  Miller, Bastian; Lindlau, Jessica; Bommert, Max; Neumann, Andre; Yamaguchi, Hisato; Holleitner, Alexander; Högele, Alexander & Wurstbauer, Ursula
  
• Control of the orbital character of indirect excitons in MoS2-WS2 heterobilayers. Physical Review B, 101(12).
  Kiemle, Jonas; Sigger, Florian; Lorke, Michael; Miller, Bastian; Watanabe, Kenji; Taniguchi, Takashi; Holleitner, Alexander & Wurstbauer, Ursula
  
• Laterally Extended States of Interlayer Excitons in Reconstructed MoSe 2/WSe2 Heterostructures
  J. Figueiredo
  
• Light–matter interaction in van der Waals hetero-structures. Journal of Physics: Condensed Matter, 32(33), 333002.
  Deilmann, Thorsten; Rohlfing, Michael & Wurstbauer, Ursula
  
• Signatures of a degenerate many-body state of interlayer excitons in a van der Waals heterostack. Physical Review Research, 2(4).
  Sigl, Lukas; Sigger, Florian; Kronowetter, Fabian; Kiemle, Jonas; Klein, Julian; Watanabe, Kenji; Taniguchi, Takashi; Finley, Jonathan J.; Wurstbauer, Ursula & Holleitner, Alexander W.
  
• Bose‐Einstein‐Kondensat aus Exzitonen?. Physik in unserer Zeit, 52(3), 140-145.
  Wurstbauer, Ursula & Holleitner, Alexander W.
  
• Exciton Manifolds in Highly Ambipolar Doped WS2. Nanomaterials, 12(18), 3255.
  Tiede, David Otto; Saigal, Nihit; Ostovar, Hossein; Döring, Vera; Lambers, Hendrik & Wurstbauer, Ursula
  
• Exotische Exzitonen. Physik Journal 21 (1), pp22-23 (2022)
  T. Stiehm & U. Wurstbauer
  
• Graphene and Beyond: Recent Advances in Two-Dimensional Materials Synthesis, Properties, and Devices, ACS Nanosci. Au 2, 450 (2022)
  Y. Lei
  
• Optical dipole orientation of interlayer excitons in MoSe2 − WSe2 heterostacks, Phys. Rev. B 105, 035417 (2022)
  L. Sigl
  
• Spectroscopic imaging ellipsometry of two-dimensional TMDC heterostructures. Applied Physics Letters, 121(7).
  Sigger, Florian; Lambers, Hendrik; Nisi, Katharina; Klein, Julian; Saigal, Nihit; Holleitner, Alexander W. & Wurstbauer, Ursula
  
• Exciton-phonon scattering: Competition between the bosonic and fermionic nature of bound electron-hole pairs. Physical Review B, 108(12).
  Katzer, Manuel; Selig, Malte; Sigl, Lukas; Troue, Mirco; Figueiredo, Johannes; Kiemle, Jonas; Sigger, Florian; Wurstbauer, Ursula; Holleitner, Alexander W. & Knorr, Andreas
  
• Extended Spatial Coherence of Interlayer Excitons in MoSe2\WSe2 Heterobilayers, Phys. Rev. Lett. 131, 036902 (2023)
  M. Troue
  
• Collective Charge Excitations between Moiré Minibands in Twisted WSe2 Bilayers Probed with Resonant Inelastic Light Scattering. Physical Review Letters, 133(4).
  Saigal, Nihit; Klebl, Lennart; Lambers, Hendrik; Bahmanyar, Sina; Antić, Veljko; Kennes, Dante M.; Wehling, Tim O. & Wurstbauer, Ursula
  
• Evidence for chiral graviton modes in fractional quantum Hall liquids. Nature, 628(8006), 78-83.
  Liang, Jiehui; Liu, Ziyu; Yang, Zihao; Huang, Yuelei; Wurstbauer, Ursula; Dean, Cory R.; West, Ken W.; Pfeiffer, Loren N.; Du, Lingjie & Pinczuk, Aron
  
• Interlayer and Moiré excitons in atomically thin double layers: From individual quantum emitters to degenerate ensembles. MRS Bulletin, 49(9), 914-931.
  Brotons-Gisbert, Mauro; Gerardot, Brian D.; Holleitner, Alexander W. & Wurstbauer, Ursula
  
• Orientation Dependent Interlayer Coupling in Organic–Inorganic Heterostructures. Advanced Functional Materials, 34(28).
  Bartlam, Cian; Saigal, Nihit; Heiserer, Stefan; Lambers, Hendrik; Wurstbauer, Ursula & Duesberg, Georg S.
  
• Scanning Acousto‐Optoelectric Spectroscopy on a Transition Metal Dichalcogenide Monolayer. Advanced Materials, 36(49).
  Nysten, Emeline D. S.; Weiß, Matthias; Mayer, Benjamin; Petzak, Tobias M.; Wurstbauer, Ursula & Krenner, Hubert J.