Bulletin of the American Physical Society
APS March Meeting 2023
Volume 68, Number 3
Las Vegas, Nevada (March 5-10)
Virtual (March 20-22); Time Zone: Pacific Time
Session S21: Plasmons in 2D Materials |
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Sponsoring Units: DCMP Chair: Yaohua Liu, Oak Ridge National Lab Room: Room 213 |
Thursday, March 9, 2023 8:00AM - 8:12AM |
S21.00001: Scattering-Type Scanning Near-Field Optical Microscopy with Akiyama Piezo-Probes in High Magnetic Fields Michael Dapolito, Makoto Tsuneto, Wenjun Zheng, Lukas Wehmeier, Suheng Xu, Xinzhong Chen, Jiacheng Sun, Zengyi Du, Zengyi Du, Yinming Shao, Ran Jing, Shuai Zhang, Yinan Dong, Dorri Halbertal, Zijian Zhou, Adrian Gozar, G.Lawrence Carr, Michael M Fogler, Alexey B Kuzmenko, Qiang Li, Dmitri N Basov, Xu Du, Mengkun Liu Recent developments of the scattering-type scanning near-field optical microscope at cryogenic temperatures (cryo-SNOM) have led to many breakthroughs in the studies of low energy excitations in quantum materials. However, the simultaneous demands on vibration isolation, low base temperature, precise nano-positioning, and optical access make the construction of a cryo-SNOM a daunting task. Adding to the overhead space required for a cryo-SNOM is the atomic force microscopy (AFM) control, which predominantly utilizes a laser-based detection scheme for determining the cantilever tapping motion. Here we provide an alternative and simplified route for performing s-SNOM using metal-coated Akiyama probes, where the cantilever tapping motion is detected through a piezoelectric signal. The Akiyama-based cryo-SNOM attains high spatial resolution, good near-field contrast, and can perform imaging with a significantly more compact system compared to other cryo-SNOM techniques. By combining this system with a 7 T magnetic field, we have directly imaged Dirac magnetoplasmons in charge-neutral monolayer graphene with subwavelength resolution. These magnetoplasmons manifest as edge interference patterns in the optical signal and as interesting edge currents in the photocurrent signal. |
Thursday, March 9, 2023 8:12AM - 8:24AM |
S21.00002: Asymmetric plasmon damping and abnormal thermoelectric current by electron-phonon instability Yinan Dong, Zhiyuan Sun, Denis A Bandurin, Isabelle Y Phinney, Trond I Andersen, Dihao Sun, Lin Xiong, Yinming Shao, Song Liu, Shuai Zhang, Pablo Jarillo-Herrero, Cory R Dean, Michael M Fogler, Dmitri N Basov Plasmons polaritons, a collective mode of electron oscillations hybridized with light, assists a plethora of physical processes, such as optical-electrical energy conversion and optical nonreciprocity. Therefore, it is important to understand the interaction between plasmon polaritons and other degrees of freedom, such as phonons and Dirac electron flow. Here we find that highly doped and biased graphene displays unconventional asymmetric plasmon damping and unexpected photocurrent sign-changes. Using cryogenic scanning nearfield microscope, noticeable difference in propagation length of graphene plasmon polaritons is observed at the same launcher for different current directions. Along with this, an abnormal sign-flip of thermoelectric current close to contacts reveals potential new mechanism for tip-based nano-photocurrent generation. Cherenkov emission of acoustic phonons can explain both the asymmetric plasmon damping and the abnormal photocurrent behavior in highly biased graphene. The observations facilitate the understanding of impacts by non-equilibrium phonons on plasmon polaritons and thermoelectric current. |
Thursday, March 9, 2023 8:24AM - 8:36AM |
S21.00003: THz nano-imaging of long wavelength graphene plasmons Rocco A Vitalone, Ran Jing, Daniel J Rizzo, Bjarke S Jessen, Valerie Hsieh, Suheng Xu, David G Mandrus, Cory R Dean, James C Hone, Dmitri N Basov Propagating plasmon polaritons in gate tunable graphene devices have been extensively studied throughout the mid-IR frequency range using scanning near-field optical microscopy (SNOM). Recent works have shown that graphene can be doped to exceedingly high carrier concentrations when in contact with certain materials via a charge transfer process (CT). A candidate quantum spin liquid material, a-RuCl3 is a prime example of this work function mediated CT, hole doping graphene with ~1013 cm-2 carriers. In this work, we study graphene/a-RuCl3 heterostructures with THz light using our home-built, cryogenic THz-SNOM. Using phase resolved imaging techniques, we can clearly observe long wavelength, heavily damped THz plasmon polaritons. These observations allow us to extract the plasmonic wavelength, λ, and quality factor, Q, in graphene/a-RuCl3 heterostructures, which together fully define the complex conductivity of the heterostructures in the THz range. We find that the plasmonic wavelength matches well with expected values for n ~1013 cm-2, while the plasmonic scattering rate is almost four times larger than in pristine graphene. Thus, we can conclude that the dielectric environment of the samples leads to much higher plasmonic damping. One possible interpretation of this result is that the a-RuCl3 is doped sufficiently, via the same CT process, to support free carriers that screen the plasmonic response in graphene. |
Thursday, March 9, 2023 8:36AM - 8:48AM |
S21.00004: Surface plasmons induce topological transition in graphene/α-MoO3 heterostructures Francesco L Ruta, Brian S Kim, Zhiyuan Sun, Daniel J Rizzo, Alexander S McLeod, Anjaly Rajendran, Song Liu, Andrew Millis, James C Hone, Dmitri N Basov Polaritons in hyperbolic van der Waals materials—where principal axes have permittivities of opposite signs—are light-matter modes with unique properties and promising applications. Isofrequency contours of hyperbolic polaritons may undergo topological transitions from open hyperbolas to closed ellipse-like curves, prompting an abrupt change in physical properties. Electronically-tunable topological transitions are especially desirable for future integrated technologies but have yet to be demonstrated. In this work, we present a doping-induced topological transition effected by plasmon-phonon hybridization in graphene/α-MoO3 heterostructures. Scanning near-field optical microscopy was used to image hybrid polaritons in graphene/α-MoO3. We demonstrate the topological transition and characterize hybrid modes, which can be tuned from surface waves to bulk waveguide modes, traversing an exceptional point arising from the anisotropic plasmon-phonon coupling. Graphene/α-MoO3 heterostructures offer the possibility to explore dynamical topological transitions and directional coupling that could inspire new nanophotonic and quantum devices. |
Thursday, March 9, 2023 8:48AM - 9:00AM |
S21.00005: Confinement of plasmons in a graphene cavity Johannes Geurs, Yinan Dong, Dmitri N Basov, Cory R Dean
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Thursday, March 9, 2023 9:00AM - 9:12AM |
S21.00006: Infrared Plasmons Propagate through a Hyperbolic Nodal Metal Yinming Shao, Aaron Sternbach, Brian S Kim, Andrey A Rikhter, Xinyi Xu, Umberto De Giovannini, Ran Jing, Sang Hoon Chae, Zhiyuan Sun, Seng Huat Lee, Yanglin Zhu, Zhiqiang Mao, James C Hone, Raquel Queiroz, Andrew Millis, James Schuck, Angel Rubio, Michael M Fogler, Dmitri N Basov Metals are canonical plasmonic media at infrared and optical wavelengths, allowing one to guide and manipulate light at the nano-scale. A special form of optical waveguiding is afforded by highly anisotropic crystals revealing the opposite signs of the dielectric functions along orthogonal directions. These media are classified as hyperbolic and include crystalline insulators, semiconductors and artificial metamaterials. Layered anisotropic metals are also anticipated to support hyperbolic waveguiding. Yet this behavior remains elusive, primarily because interband losses arrest the propagation of infrared modes. Here, we report on the observation of propagating hyperbolic waves in a prototypical layered nodal-line semimetal ZrSiSe [1]. The observed waveguiding originates from polaritonic hybridization between near-infrared light and nodal-line plasmons. Unique nodal electronic structures simultaneously suppress interband loss and boost the plasmonic response, ultimately enabling the propagation of infrared modes through the bulk of the crystal. |
Thursday, March 9, 2023 9:12AM - 9:24AM |
S21.00007: Toward Wide-Area Exciton-Polaritons in a Transferrable DBR Microcavity Rui Xue, Qiaochu Wan, Jonathan C Beaumariage, Xingzhou Chen, Min Zhang, Qiuyang Li, Bin Liu, Sayema Chowdhury, Zheng Sun, Sanjay Banerjee, Stephen R Forrest, Hui Deng, David W Snoke Optical microcavities made by distributed Bragg reflectors (DBRs) have a strong wavelength-selection property, playing a significant role in studying light-matter coupling. When the confined photon energy is in resonant with the exciton, they will strongly couple with each other, leading to a new quasiparticle state called an exciton-polaritons. Recently, transition metal dichalcogenides (TMD) monolayers, with tightly bound excitons and strong optical response, have emerged as new candidates for polariton studies. However, traditional methods of making TMD monolayers generate small (ca. 10 microns) flakes, while we would like to see long-distance transport effects when the polaritons undergo spontaneous thermalized Bose-Einstein condensation in 2D systems. To accomplish this, we need a high-quality, flat, and wide-area top DBR and a large-area monolayer. Here we discuss our progress using new fabrication methods (cf. [1-2]) with great potential in achieving large-scale polariton condensation in 2D materials. |
Thursday, March 9, 2023 9:24AM - 9:36AM |
S21.00008: Electrically switchable in-plane anisotropic exciton-polariton in a van der Waal semiconductor Yue Luo, Nannan Mao, Dapeng Ding, Ming-Hui Chiu, Xiang Ji, Kenji Watanabi, Takashi Taniguchi, Vincent Tung, Hongkun Park, Philip Kim, Jing Kong, William L Wilson Tailoring of the propagation dynamics of exciton-polaritons in two-dimensional quantum materials has shown extraordinary promise to enable nanoscale control of electromagnetic fields. Varying permittivities along crystal directions within layers of material systems, can lead to an in-plane anisotropic dispersion of polaritons. Exploiting this physics as a control strategy for manipulating the directional propagation of the polaritons is desired and remains elusive. Here, we explore the in-plane anisotropic exciton-polariton propagation in a group-IV monochalcogenide semiconductor which forms ferroelectric domains and exhibits room-temperature excitonic behavior. Exciton-polaritons with their propagation dynamics and dispersion studied. This propagation of exciton-polaritons allows for nanoscale imaging of the in-plane ferroelectric domains. Finally, we demonstrate the electric switching of the exciton-polaritons in the ferroelectric domains of this complex vdW system. The study suggests that systems like group-IV monochalcogenides could serve as excellent ferroic platforms for actively reconfigurable polaritonic optical devices. |
Thursday, March 9, 2023 9:36AM - 9:48AM |
S21.00009: Negative refraction in hyperbolic hetero-bicrystals Aaron Sternbach, Samuel L Moore, Andrey A Rikhter, Shuai Zhang, Ran Jing, Yinming Shao, Brian S Kim, Suheng Xu, Song Liu, James H Edgar, Angel Rubio, Cory R Dean, James C Hone, Michael M Fogler, Dmitri N Basov Select quantum materials can support polaritons, hybrid light matter waves, with sub-diffraction-limited confinement. In this talk, I will overview recent progress on polaritons in hyperbolic materials, which propagate as conical rays throughout the bulk of these crystals. I will discuss polaritons in a class of hyperbolic hetero-bicrystals. Our data reveals negative refraction, spectral gaps and wave localization in these systems [1]. |
Thursday, March 9, 2023 9:48AM - 10:00AM |
S21.00010: Tuning across vibrational light-matter coupling regimes in van der Waals crystals Thibault Chervy, Etienne LORCHAT, Shang-Jie Yu, Helen Yao, Jenny Hu, Jonathan A Fan, Tony F Heinz The strong light-matter coupling regime is achieved when the dipolar transition of a material hybridizes with a confined optical resonance. In this regime new polaritonic eigen-states are formed, with shared optical and material character. While such states have long been studied in the context of non-linear optics, recent experiments reported dramatic modifications of physico-chemical properties of materials upon the formation of polaritonic states. These reports range from enhanced energy and charge transfers, to the modification of chemical reaction pathways. |
Thursday, March 9, 2023 10:00AM - 10:12AM |
S21.00011: Lifetime limited and tunable quantum emitters in hexagonal boron nitride Hamidreza Akbari, Souvik Biswas, Joeson Wong, Pankaj K Jha, Benjamin Vest, Harry Atwater Color centers in hexagonal boron nitride (h-BN) are bright stable sources of quantum light in the visible range of the spectrum. Spectral broadening mechanisms such as spectral diffusion have limited the application of these emitters in many quantum communication technologies as it prevents the emitters to reach their fundamental Fourier transform limit. Here we report tunable nearly lifetime limited single photon emitters in h-BN located in a fully Van der Waals device consisting of Graphene and h-BN. We suppress spectral diffusion by applying an electrostatic field at cryogenic temperature of 6.5K, The linewidth measured via photoluminescence excitation shows two orders of magnitude reduction from 8.5 GHz down to 89 MHz. Furthermore, we show Stark tunability of 2.7meV/(V/nm) over a range of 400 GHz. Our findings can be utilized for on-chip quantum technologies based on h-BN emitters. |
Thursday, March 9, 2023 10:12AM - 10:24AM |
S21.00012: Photon bunching of interlayer exciton electroluminescence in atomically thin semiconductor heterostructures Andres M Mier Valdivia, Nadine Leisgang, Andrew Joe, Dapeng Ding, Jue Wang, Daniel Rhodes, Bumho Kim, Song Liu, Kenji Watanabe, Takashi Taniguchi, James C Hone, Mikhail D Lukin, Hongkun Park, Philip Kim Atomically thin semiconductor heterostructures are an ideal system for exploring strong light-matter interactions in the 2D limit. When electrons and holes are individually injected into these materials, they can bind to form interlayer excitons that emit light when they recombine. In this work, we study the electroluminescence of interlayer excitons in MoSe2/WSe2-based heterostructures under a forward bias. In particular, we performed measurements of the second order correlation function and observed photon bunching for a range of bias voltages. We discuss the origin of this bunched electroluminescence and what it elucidates about the quantum state of the interlayer excitons. |
Thursday, March 9, 2023 10:24AM - 10:36AM Author not Attending |
S21.00013: Electron-phonon processes in low symmetry 2Dmaterials investigated by polarized and resonance Raman spectroscopy MARCOS A PIMENTA, Luis Balicas, Mauricio Terrones, Daniel A Rhodes, Orlando J Silveira, Mário S.C. Mazzoni, Geovani Carvalho de Resende, Jessica S Lemos, Guilherme A Ribeiro, Bruno R Carvalho, Cristiano Fantini Raman spectroscopy is a powerful tool to study the behavior of phonons in optically anisotropic 2D materials since the intensities of the Raman peaks depend on the polarization of the light with respect to the crystallographic axes. I will present angle-resolved polarized Raman measurements in single-layer (1L) and bulk ReSe2 and ReS2 crystals that exhibit a triclinic symmetry, and using different laser excitation energies. Angle-resolved results allows the investigation of the effect of dimensionality on the Raman tensors, and the multiple excitation experiments exhibit peak enhancements by both single and the double-resonance processes. Phase differences between tensor elements are needed to describe the experimental results for low symmetry 2D crystals and results are explained considering the quantum model for the Raman intensities and the fact that Raman tensor elements are complex numbers near resonances. I will finally show that the wavevector dependence of the electron–phonon interaction is essential for explaining the distinct angle-resolved results for the different phonon modes of ReSe2 and ReS2. |
Thursday, March 9, 2023 10:36AM - 10:48AM |
S21.00014: Probing the Effect of Dye-2D Material Configuration on their Surface Enhanced Raman Spectra Arpit Jain Graphene-enhanced Raman Spectroscopy (GERS) is a powerful technique enabling reproducible and sensitive detection of various biochemical species enabled by graphene’s atomically flat surface, charge transfer characteristics and high quenching ability. GERS works on the highly charge and surface-sensitive mechanism of chemical enhancement and thus requires an in-depth understanding of the analyte-graphene interaction to tune the overall enhancement. Here we choose planar and non-planar dye molecules from the Rhodamine family as analytes and study their GERS enhancement in two configurations: dye on top or bottom of graphene. For dyes on top of graphene, we observe a very high enhancement for stretching vibrational modes and a greater degree of fluorescence quenching, indicating more significant dye molecule adsorption than the dye-on-bottom configuration. Non-planar dye molecules also show an abnormal enhancement of vibrational modes associated with out-of-plane chemical species implying their flattening to increase conformity with the graphene surface, which is not observed in the case of planar dye molecules or on top of MoS2 thus showing the importance of structural matching in GERS. First principle calculations of the resonance Raman spectra assignments of the dye molecules support the experimentally observed molecular flattening. Our work gives a deeper understanding of the effect of analyte-graphene interaction on GERS signals and paves the way for a robust graphene-based platform for biochemical sensing. |
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