Article
Multidisciplinary Sciences
Jack B. Muir, Jesper Levinsen, Stuart K. Earl, Mitchell A. Conway, Jared H. Cole, Matthias Wurdack, Rishabh Mishra, David J. Ing, Eliezer Estrecho, Yuerui Lu, Dmitry K. Efimkin, Jonathan O. Tollerud, Elena A. Ostrovskaya, Meera M. Parish, Jeffrey A. Davis
Summary: Researchers introduced mobile exciton impurities into a two-dimensional electron gas and conducted experiments on monolayer WS2 using multi-dimensional coherent spectroscopy. They found that at low electron doping densities, the dominant interactions occur between polaron states dressed by the same Fermi sea. Additionally, they discovered a bipolaron bound state with remarkably large binding energy involving excitons in different valleys cooperatively bound to the same electron.
NATURE COMMUNICATIONS
(2022)
Article
Chemistry, Physical
Byeong Geun Jeong, Chanwoo Lee, Sung Hyuk Kim, Seok Joon Yun, Dong Hyeon Kim, Juchan Lee, Dongki Lee, Ki Kang Kim, Seong Chu Lim, Mun Seok Jeong
Summary: Defect analysis in two-dimensional transition-metal dichalcogenides (TMDs) is important due to its significant impact on the optical and electrical properties of TMD. This study investigated the influence of sulfur vacancies and oxygen substitution on the optical properties of WS2 using laser irradiation technique. The defect-induced photoluminescence (PL) exhibited distinct features depending on the type of defects, resulting in changes in the intensities and peak positions of excitons, biexcitons, and defect-bound excitons. Defect-activated Raman modes provided information about the defects and revealed the origin of the alteration in PL.
JOURNAL OF PHYSICAL CHEMISTRY C
(2022)
Article
Nanoscience & Nanotechnology
Ankur Sharma, Yi Zhu, Robert Halbich, Xueqian Sun, Linglong Zhang, Bowen Wang, Yuerui Lu
Summary: This study reports the highest exciton diffusion coefficient value in monolayer WS2 achieved by engineering the radiative lifetime and diffusion lengths using electrostatic doping and substrate engineering. The diffusion coefficient of excitons is significantly increased, reaching an extremely high value that has not been reported before in TMDCs. The dynamic and spatial diffusion of excitons, trions, and biexcitons can also be controlled at low temperatures. These findings establish monolayer TMDCs as ideal candidates for high-speed excitonic circuits, optoelectronic, and photonic device applications.
ACS APPLIED MATERIALS & INTERFACES
(2022)
Article
Optics
Jinping Chen, Yizhi Zhu, Heng Guo, Qiannan Cui, Zengliang Shi, Chunxiang Xu
Summary: In this study, the excitonic populations in monolayer WS2 were modulated by decorating it with Rhodamine 6G (R6G), resulting in a strong quenching of the photoluminescence (PL) and an increase in the spectral weight of trions. The type-II energy band alignment of the WS2/R6G heterointerface facilitated the photoinduced electron transfer from R6G to WS2 and hole transfer from WS2 to R6G, leading to a reduction in exciton population.
JOURNAL OF LUMINESCENCE
(2023)
Article
Chemistry, Multidisciplinary
Biao Wu, Haihong Zheng, Shaofei Li, Junnan Ding, Yujia Zeng, Zongwen Liu, Yanping Liu
Summary: Moire superlattices provide a platform for designing the properties of optical excitons and enable the exploration of topological excitons and quantum emitters. This study observes moire excitons in the WS2/WS2 T-HS and investigates the effect of temperature and laser power on the excitons.
Article
Chemistry, Multidisciplinary
Pei-Gang Chen, Zhiyong Li, Yun Qi, Tsz Wing Lo, Shubo Wang, Wei Jin, Kwok-Yin Wong, Shanhui Fan, Anatoly Zayats, Dangyuan Lei
Summary: The research demonstrates a valleytronic system based on high-quantum-yield trion emission in monolayer WS2, chirally coupled to a low-loss microfiber, achieving long-range directional routing of valley excitations and selective address of valley-dependent emission from different spatial locations. This valleytronic interface can be integrated with fiber communication devices, providing a new mechanism for optical information transport and manipulation in classical and quantum regimes.
Article
Multidisciplinary Sciences
Suman Chatterjee, Medha Dandu, Pushkar Dasika, Rabindra Biswas, Sarthak Das, Kenji Watanabe, Takashi Taniguchi, Varun Raghunathan, Kausik Majumdar
Summary: Excitonic states trapped in harmonic moire wells of twisted heterobilayers offer a unique platform for studying many-body physics. In this study, we demonstrate anharmonic tuning of the moire potential in a WS2/WSe2 heterobilayer through gate voltage and optical power. By applying a gate voltage, we can observe both linear and parabolic Stark shifts for the ground state and first excited state, respectively, of the moire-trapped exciton. Additionally, the exciton localization-dependent dipolar repulsion results in a power-induced blueshift that is five times greater than previous reports.
NATURE COMMUNICATIONS
(2023)
Article
Physics, Multidisciplinary
Di Huang, Kevin Sampson, Yue Ni, Zhida Liu, Danfu Liang, Kenji Watanabe, Takashi Taniguchi, Hebin Li, Eric Martin, Jesper Levinsen, Meera M. Parish, Emanuel Tutuc, Dmitry K. Efimkin, Xiaoqin Li
Summary: When mobile impurities are introduced and coupled to a Fermi sea, new quasiparticles called Fermi polarons are formed. There are two regimes of the Fermi polaron problem: attractive polarons (AP) connected to pairing phenomena, and repulsive polarons (RP) responsible for ferromagnetism. In this study, we investigate Fermi polarons in a doped MoSe2 monolayer and find agreement with polaron theory for attractive polarons. The dynamics of Fermi polarons are important for understanding pairing and magnetic instabilities in various physical systems.
Article
Materials Science, Multidisciplinary
Xu-Chen Yang, Hongyi Yu, Wang Yao
Summary: In monolayers of semiconducting transition metal dichalcogenides, dielectric patterning can control the strength of electron-hole exchange interaction through the dielectric environment, achieving different waveguide effects for the transverse and longitudinal branch excitons.
Article
Materials Science, Multidisciplinary
D. Beret, L. Ren, C. Robert, L. Foussat, P. Renucci, D. Lagarde, A. Balocchi, T. Amand, B. Urbaszek, K. Watanabe, T. Taniguchi, X. Marie, L. Lombez
Summary: We investigated the diffusion process of negatively charged excitons in a WSe2 monolayer and found nonlinear diffusion behavior. The dynamics of different excitonic species were examined, and a bimolecular formation mechanism was proposed. Based on our experimental observations, a phenomenological model suggesting the coexistence of two populations, with different diffusion mechanisms, was proposed.
Article
Optics
Shaofei Li, Haihong Zheng, Biao Wu, Junnan Ding, Jun He, Zongwen Liu, Yanping Liu
Summary: In this study, we investigated the polarization of excitonic valleys in MoS2-WS2 heterostructures using circular polarization-resolved photoluminescence. The valley polarization was found to be the highest in the 1L-1L MoS2-WS2 heterostructure, and the polarizability of A(WS2) decreased with increasing number of WS2 layers. We also observed a redshift of the exciton X-MoS2(-) in MoS2-WS2 heterostructures as the number of WS2 layers increased, which can be attributed to the displacement of the MoS2 band edge and indicates the layer-sensitive optical properties of the MoS2-WS2 heterostructure.
Article
Chemistry, Multidisciplinary
Bumho Kim, Yue Luo, Daniel Rhodes, Yusong Bai, Jue Wang, Song Liu, Abraham Jordan, Baili Huang, Zhaochen Li, Takashi Taniguchi, Kenji Watanabe, Jonathan Owen, Stefan Strauf, Katayun Barmak, Xiaoyang Zhu, James Hone
Summary: In MoSe2 monolayers, the quantum yield of trions increases with decreasing defect density, with a long lifetime of approximately 230 ps allowing for direct observation of their diffusion.
Article
Chemistry, Multidisciplinary
Jiajun Chen, Xiaofei Yue, Yabing Shan, Huishan Wang, Jinkun Han, Haomin Wang, Chenxu Sheng, Laigui Hu, Ran Liu, Weihuang Yang, Zhi-Jun Qiu, Chunxiao Cong
Summary: This study reports the influence of twist angle on interlayer excitons in the WSe2/WS2 heterostructure, and confirms the existence of direct and indirect interlayer excitons through photoluminescence and density functional theory calculations. By applying an external electric field to regulate the band structure and transition path of interlayer excitons, the regulation of interlayer exciton emission was successfully achieved.
Article
Chemistry, Multidisciplinary
Malgorzata Zinkiewicz, Tomasz Wozniak, Tomasz Kazimierczuk, Piotr Kapuscinski, Kacper Oreszczuk, Magdalena Grzeszczyk, Miroslav Bartos, Karol Nogajewski, Kenji Watanabe, Takashi Taniguchi, Clement Faugeras, Piotr Kossacki, Marek Potemski, Adam Babinski, Maciej R. Molas
Summary: In this study, the origin of emission lines in the low-temperature photoluminescence spectra of n-doped WS2 monolayer embedded in hexagonal BN layers was investigated using external magnetic fields and first-principles calculations. Different families of emissions due to exciton complexes in WS2 were identified based on experimentally extracted and theoretically calculated g-factors, as well as the determination of g-factors of the spin-split subbands in both the conduction and valence bands.
Article
Chemistry, Multidisciplinary
Zachariah Hennighausen, Jisoo Moon, Kathleen M. McCreary, Connie H. Li, Olaf M. J. van 't Erve, Berend T. Jonker
Summary: The assembly of 2D materials in van der Waals heterostructures offers opportunities in materials design and synthesis. In this study, we report the formation of interlayer exciton-phonon bound states in Bi2Se3/WS2 heterostructures. These bound states appear as evenly separated peaks in the WS2 excitonic photoluminescence spectrum, corresponding to the energy of the A(1)((3)) surface phonon in Bi2Se3. Our work enhances understanding of interlayer van der Waals interactions and facilitates the development of technologies for spintronics, valleytronics, and quantum computing applications.
Article
Physics, Applied
Robert Schneider, Mario Fix, Jannis Bensmann, Steffen Michaelis de Vasconcellos, Manfred Albrecht, Rudolf Bratschitsch
Summary: We measured the transient THz emission of ultrathin spintronic bilayers consisting of a cobalt-iron alloy and platinum, and found that the THz emission amplitude changes only slightly with varying cobalt content. Additionally, we fabricated multilayer stacks and observed an increase of up to 36% in THz amplitude compared to a single bilayer CoFe/Pt spintronic emitter.
APPLIED PHYSICS LETTERS
(2022)
Review
Physics, Condensed Matter
Steffen Michaelis de Vasconcellos, Daniel Wigger, Ursula Wurstbauer, Alexander W. Holleitner, Rudolf Bratschitsch, Tilmann Kuhn
Summary: This review article provides an overview of single-photon emitters (SPEs) in layered van der Waals materials, including their physical properties, theoretical models, creation techniques, and potential applications in quantum information, communication, and optomechanical devices. It also briefly discusses functionalities beyond single-photon emission.
PHYSICA STATUS SOLIDI B-BASIC SOLID STATE PHYSICS
(2022)
Article
Nanoscience & Nanotechnology
Alexander Eich, Tobias C. Spiekermann, Helge Gehring, Lisa Sommer, Julian R. Bankwitz, Philip P. J. Schrinner, Johann A. Preuss, Steffen Michaelis de Vasconcellos, Rudolf Bratschitsch, Wolfram H. P. Pernice, Carsten Schuck
Summary: This study reports on the integration of individual colloidal core-shell quantum dots into a nanophotonic network, allowing for excitation and efficient collection of single photons through separate waveguide channels. The use of an iterative electron beam lithography process enables the positioning of single emitters on a chip with a high yield. This work goes beyond traditional bulk optic methods and provides a pathway for supplying chip-scale quantum networks with single photons from a large number of simultaneously controllable quantum emitters.
Article
Materials Science, Multidisciplinary
Joshua J. P. Thompson, Samuel Brem, Marne Verjans, Robert Schmidt, Steffen Michaelis de Vasconcellos, Rudolf Bratschitsch, Ermin Malic
Summary: Energy transport is crucial for the efficiency of optoelectronic applications. By manipulating strain and dielectric engineering, we demonstrate the possibility to control the speed and direction of exciton diffusion.
Article
Materials Science, Multidisciplinary
Julian Sickel, Marcel Asbach, Christoph Gammer, Rudolf Bratschitsch, Helmut Kohl
Summary: In this study, a novel method using scanning nanobeam electron diffraction (NBED) is introduced to obtain quantitative strain and topography information of 2D materials. The method can accurately measure both strain and slope by reconstructing the reciprocal lattice rods' positions and orientations. Experimental and simulation results demonstrate the effectiveness of the method.
MICROSCOPY AND MICROANALYSIS
(2022)
Article
Chemistry, Multidisciplinary
Johann A. Preuss, Helge Gehring, Robert Schmidt, Lin Jin, Daniel Wendland, Johannes Kern, Wolfram H. P. Pernice, Steffen Michaelis de Vasconcellos, Rudolf Bratschitsch
Summary: The article presents a method using ultralow fluorescence photopolymer to 3D print micrometer-sized elliptical lenses on hBN nanocrystals for efficiently collecting light from single-photon emitters. The method is experimentally confirmed to successfully collect single photons without disturbing their characteristics. This approach is highly significant for the application of photonic quantum technologies.
Article
Chemistry, Multidisciplinary
Julian Klein, Benjamin Pingault, Matthias Florian, Marie-Christin Heissenbuettel, Alexander Steinhoff, Zhigang Song, Kierstin Torres, Florian Dirnberger, Jonathan B. Curtis, Mads Weile, Aubrey Penn, Thorsten Deilmann, Rami Dana, Rezlind Bushati, Jiamin Quan, Jan Luxa, Zdenek Sofer, Andrea Alu, Vinod M. Menon, Ursula Wurstbauer, Michael Rohlfing, Prineha Narang, Marko Loncar, Frances M. Ross
Summary: In this study, it was found that the magnetic semiconductor CrSBr behaves like a quasi-1D material in a magnetically ordered environment. The strong 1D electronic character of CrSBr originates from the Cr-S chains and the weak interlayer hybridization, leading to anisotropy in effective mass and dielectric screening. Moreover, CrSBr hosts spectrally narrow excitons of high binding energy and oscillator strength due to reduced dimensionality and interlayer coupling. Overall, CrSBr is an experimentally attractive candidate for the study of exotic exciton and 1D-correlated many-body physics.
Correction
Chemistry, Physical
Johannes Tolle, Thorsten Deilmann, Michael Rohlfing, Johannes Neugebauer
JOURNAL OF CHEMICAL THEORY AND COMPUTATION
(2023)
Review
Chemistry, Physical
Thorsten Deilmann, Michael Rohlfing, Kristian Sommer Thygesen
Summary: Two-dimensional (2D) materials possess unique physical and chemical properties, and their optical properties can be easily modified. This review focuses on the theoretical description of the excited states and optical properties of 2D semiconductors, specifically addressing the challenges and opportunities. Results are presented for transition metal dichalcogenides, their heterostructures, and novel materials from the computational 2D materials database.
ELECTRONIC STRUCTURE
(2023)
Article
Materials Science, Multidisciplinary
Vishwas Jindal, Thorsten Deilmann, Sandip Ghosh
Summary: The interlayer exciton (IL) in bilayer 2H-MoS2 undergoes large Stark splitting under electric field, and the excited state exciton A2s in bulk 2H-MoS2 undergoes three times as large splitting with a dipole moment magnitude. The nature and evolution of different exciton species with electric field are verified by ab initio calculations, and the results show the individual character of exciton states at high electric field.
Correction
Chemistry, Physical
Johannes Neugebauer, Thorsten Deilmann, Michael Rohlfing, Johannes Neugebauer
JOURNAL OF CHEMICAL THEORY AND COMPUTATION
(2023)
Article
Materials Science, Multidisciplinary
P. Marauhn, M. Rohlfing
Summary: The electronic and optical properties of layered materials are affected by the image charge effect, which is caused by the dielectric environment. This effect varies between layers in multilayer structures, but its implications on interlayer coupling are not well understood. A macroscopic dielectric continuum model is proposed to describe the variation of dielectric screening effects, and an efficient method for incorporating this effect in electronic structure calculations is presented. By applying this method to multilayer MoS2, an energetic decoupling of the surface layer is observed, leading to the formation of a surface-layer band gap. Furthermore, the image charge effect can cause spatial modulation of interlayer coupling by changing the band alignment between layers.
Article
Materials Science, Multidisciplinary
Iris Niehues, Thorsten Deilmann, Joanna Kutrowska-Girzycka, Alireza Taghizadeh, Leszek Bryja, Ursula Wurstbauer, Rudolf Bratschitsch, Joanna Jadczak
Summary: This study reports on the impact of strain on the Raman response of a ReS2 monolayer. By applying strain, the Raman-active phonon frequencies can be shifted to lower energies. These findings are of importance for potential future strain-sensor applications.
