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 CCC06: V: General Physics IV |
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Sponsoring Units: APS Chair: Kathleen Tatem, Tatem Research Institute Room: Virtual Room 6 |
Wednesday, March 22, 2023 3:00PM - 3:12PM |
CCC06.00001: A Novel Physical Mechanism to Model Brownian Yet Non-Gaussian Diffusion: Theory and Application francisco alban A few experiments in the fields of biological and soft matter physics in colloidal suspensions have reported "normal diffusion" with a Laplacian probability distribution in the particle's displacements (i.e., Brownian yet non-Gaussian diffusion). To model this behavior, different stochastic and microscopic models have been proposed, with the former introducing new random elements that incorporate our lack of information about the media and the latter describing a limited number of interesting physical scenarios. This incentivizes the search of a more thorough understanding of how the media interacts with itself and with the particle being diffused in Brownian yet non-Gaussian diffusion. For this reason, a comprehensive mathematical model to explain Brownian yet non-Gaussian diffusion that includes weak molecular interactions is proposed in this paper. Based on the theory of interfaces by De Gennes and Langevin dynamics, it is shown that long-range interactions in a weakly interacting fluid leads to a Laplacian probability distribution in the radial particle's displacements. Further, it is shown that a phase separation can explain a high diffusivity and causes this Laplacian distribution to evolve towards a Gaussian via a transition probability in the interval of time as it was observed in experiments. To verify these predictions, the experimental data of the Brownian motion of colloidal beads on phospholipid bilayer by Wang et al. are used and compared with the results of the theory. |
Wednesday, March 22, 2023 3:12PM - 3:24PM |
CCC06.00002: Escape dynamics of active Janus particle from porous circular cavity Tanwi Debnath Janus particle is nano to micro meter sized entity having two distinct faces, only one of which is chemically or physically active. A class of Janus particle is called self-propelled or active Janus which can move extracting energy from environment by creating concentration or thermal gradient at the vicinity of its active surface. We numerically study the mean exit time of active particle of the Janus kind from a circular cavity with single or multiple exit windows. Our simulation results witness distinct escape mechanisms depending upon the relative amplitudes of the thermal length and self-propulsion length compared to the cavity and pore sizes. For exceedingly large self-propulsion lengths, overdamped active particles diffuse on the cavity surface, and rotational dynamics solely governs the exit process. On the other hand, the escape kinetics of a very weakly damped active particle is largely dictated by bouncing effects on the cavity walls irrespective of the amplitude of self-propulsion persistent lengths. We show that the exit rate can be maximized for an optimal self-propulsion persistence length, which depends on the damping strength, self-propulsion velocity, and cavity size. However, the optimal persistence length is insensitive to the opening windows' size, number, and arrangement. The present analysis aims to understand the transport controlling mechanism of active matter in confined structures. The findings of this study can be used in medical science and nano technology. |
Wednesday, March 22, 2023 3:24PM - 3:36PM |
CCC06.00003: Curiosity as filling, compressing, and reconfiguring knowledge networks. Shubhankar Patankar, Dale Zhou, Christopher W Lynn, Jason Z Kim, mathieu ouellet, Harang Ju, Perry Zurn, David Lydon-Staley, Dani S Bassett Due to the significant role that curiosity plays in our lives, several theoretical constructs, such as the information gap theory and compression progress theory, have sought to explain how we engage in its practice. According to the former, curiosity is the drive to acquire information that is missing from our understanding of the world. According to the latter, curiosity is the drive to construct an increasingly parsimonious mental model of the world. To complement the densification processes inherent to these theories, we propose the conformational change theory, wherein we posit that curiosity results in mental models with marked conceptual flexibility. We formalize curiosity as the process of building a growing knowledge network to quantitatively investigate information gap theory, compression progress theory, and the conformational change theory of curiosity. In knowledge networks, gaps can be identified as topological cavities, compression progress can be quantified using network compressibility, and flexibility can be measured as the number of conformational degrees of freedom. We leverage data acquired from the online encyclopedia Wikipedia to determine the degree to which each theory explains the growth of knowledge networks built by individuals and by collectives. Our findings lend support to a pluralistic view of curiosity, wherein intrinsically motivated information acquisition fills knowledge gaps and simultaneously leads to increasingly compressible and flexible knowledge networks. Across individuals and collectives, we determine the contexts in which each theoretical account may be explanatory, thereby clarifying their complementary and distinct explanations of curiosity. Our findings offer a novel network theoretical perspective on intrinsically motivated information acquisition that may harmonize with or compel an expansion of the traditional taxonomy of curiosity. |
Wednesday, March 22, 2023 3:36PM - 3:48PM |
CCC06.00004: Ultra-low subthreshold swing across five-decade in 2D negative capacitance Dirac source-drain MoS2-Gr heterostructure field effect transistor Debottam Daw, Houcine Bouzid, Moonyoung Jung, Chandan Biswas, Young Hee Lee In conventional field effect transistors Boltzmann distribution sets a fundamental limit to achieve sub-60 subthreshold swing (SS) at room temperature. By converging the concepts of negative differential capacitance in 2D ferroelectric and localized density state of graphene source around the Dirac point we demonstrate a state-of-art device architecture that retains average SS of 13 mV/dec over five decades of drain current with the minimum SS of 4.8 mV/dec. The negative capacitance stems from double energy landscape in layered van der Waals material is verified by applying a voltage pulse across the CuInP2S6 capacitor and analyzing the inductance like transient voltage dynamics. Insightful investigation has been done to understand the physics behind the improved NC performance which differs from the previous reports. Further modified device structure is demonstrated, it provides mV order of hysteresis with reasonably low sub-thermionic SS. Our study could pave the way for potential ultra-low power electronics industry. |
Wednesday, March 22, 2023 3:48PM - 4:00PM |
CCC06.00005: Curvature can inhibit evaporation inside micropores GUN OH, Byung Mook Weon, Sung Hoon Kang We observe evaporation in micropores using X-ray microscopy and optical microscopy. Micropores can induce low or negative pressure inside fluids in micropores. We calculate internal pressure changes by curvature between air and fluids, particularly by controlling cavity size and ambient pressure. We explain how curvature inhibits evaporation inside micropores by competition between negative Laplace pressure (hydrodynamics) and modified vaporization pressure (thermodynamics). From our observations, small micropore size, high ambient pressure, and high relative humidity are favorable for evaporation inhibition from micropores. This finding would be crucial in understanding microscale and nanoscale phenomena regarding evaporation. |
Wednesday, March 22, 2023 4:00PM - 4:12PM |
CCC06.00006: Deploying complex shapes using kirigami José Bico, Etienne Reyssat, Benoit Roman, Joo-Won HONG, Marie Tani Kirigami is now known to be a relevant method to give stretching in thin sheets. |
Wednesday, March 22, 2023 4:12PM - 4:24PM |
CCC06.00007: Tin oxide slanted nanorod array-based optoelectronic memristor with enhanced resistive switching performance Swathi S. P. One-dimensional (1D) metal oxide-based photonic memristors, combining information storage and optical response, have shown great potential for the design and development of high-density and high-efficient computing systems beyond the era of von-Neumann architecture and Moore’s law. Here, the functional memristive devices based on SnOx slanted nanorod arrays are demonstrated; wherein both the optical and electrical stimuli can be used to modulate the switching characteristics. These exhibit excellent device parameters, including low operating voltages, currents, and longer retention in the dark. Under illumination, ranging from ultraviolet (254 and 365 nm) to visible light (400-700 nm), the unusual negative photo response with an enlarged ON/OFF ratio > 106 is observed. The optoelectronic resistive memory behaviour is attributed to the electric field-induced formation of oxygen vacancies and light-stimulated dissolution of oxygen vacancies. The results suggest that the optical illumination reduces the oxygen ion migration barrier, leading to the dissolution of conductive filaments and thereby locally increasing the OFF state resistance. In addition, the well-aligned tin oxide nanorod arrays eliminate the branching or overgrowth of the conductive filaments and significantly reduce stochasticity in the resistive switching device parameters. These results demonstrate the potential applications of metal oxide-based 1D nanostructures for optoelectronic memory applications. Such memristors, with the combination of optical and electrical stimuli, have scope in the applications of artificial visual memory and other optoelectronic systems for integrated photonic circuits. |
Wednesday, March 22, 2023 4:24PM - 4:36PM |
CCC06.00008: Efficient Ohmic contacts and built-in atomic sublayer protection in MoSi2N4 and WSi2N4 monolayers Qianqian Wang Metal contacts to two-dimensional (2D) semiconductors are often plagued by the strong Fermi level pinning (FLP) effect which reduces the tunability of the Schottky barrier height (SBH) and degrades the performance of 2D semiconductor devices. Here, we show that MoSi2N4 and WSi2N4 monolayers—an emerging 2D semiconductor family with exceptional physical properties—exhibit strongly suppressed FLP and wide-range tunable SBH. An exceptionally large SBH slope parameter of S ≈ 0.7 is obtained which outperforms the vast majority of other 2D semiconductors. Such intriguing behavior arises from the septuple-layered morphology of MoSi2N4 and WSi2N4 monolayers in which the semiconducting electronic states are protected by the outlying Si–N sublayer. We identify Ti, Sc, and Ni as highly efficient Ohmic contacts to MoSi2N4 and WSi2N4 with zero interface tunneling barrier. Our findings reveal the potential of MoSi2N4 and WSi2N4 as a practical platform for designing high-performance and energy-efficient 2D semiconductor electronic devices. |
Wednesday, March 22, 2023 4:36PM - 4:48PM |
CCC06.00009: Second harmonic generation from exciton-magnons in van der Waals antiferromagnet MnPS3 Ziqian Wang, Yuki Shiomi, Taka-hisa Arima, Naoto Nagaosa, Yoshinori Tokura, Naoki Ogawa Antiferromagnets comprise an important platform for spintronics due to their ultrafast spin dynamics. Recent discovery of two-dimensional (2D) van der Waals (vdW) antiferromagnets with strong intralayer charge-spin correlations has further sparked great interest in ultrafast opto-spintronics. The magnon-sideband of exciton, so-called exciton-magnons, has been observed in the optical absorption spectra of Néel-type vdW antiferromagnet MnPS3 [1]. Nevertheless, its origin and dynamics are far from being well understood. We will present our nonlinear optical spectroscopic characterization of exciton-magnons in MnPS3, focusing on its electronic/magnetic symmetry, and discuss their potential use in ultrafast photogeneration of magnons. |
Wednesday, March 22, 2023 4:48PM - 5:00PM |
CCC06.00010: Photo-Sensitivity and Charge Transport in Novel Narrow-Bandgap Semiconductors for Single THz Photon and Dark Matter Detection Caleb W Fink, Matthew S Cook, Samuel L Watkins, Daniele S Alves, Noah Kurinsky, Arran T Phipps, Filip Ronning, Priscila Rosa, Sean Thomas Efficient detection of single THz photons is an outstanding challenge in the fields of particle astrophysics and THz spectroscopy that would open new pathways for dark matter discovery. While single THz photon counting has been achieved with quantum dot sensors, these devices suffer from an inability to resolve the energy of individual photons. Highly pure narrow bandgap semiconductors have emerged as natural candidates for single THz energy resolvable detectors. In this talk we discuss the photosensitivity and subsequent photo-electron transport properties in a series of novel narrow bandgap materials that we have synthesized with bandgaps on the order of 10-100 meV. Resistivity measurements indicate that these candidate materials have lower dark count rates than existing photodetectors in this energy range. We further discuss how we are developing these materials into detectors to be used in the search for low mass dark matter using cryogenic based charge amplification techniques. |
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