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1. Quantum interference in superposed lattices

   https://doi.org/10.1073/pnas.2315787121  

   Feng, Yejun ; Wang, Yishu ; Rosenbaum, T. F. ; Littlewood, P. B. ; Chen, Hua ( February 2024 , Proceedings of the National Academy of Sciences)

   Charge transport in solids at low temperature reveals a material’s mesoscopic properties and structure. Under a magnetic field, Shubnikov–de Haas (SdH) oscillations inform complex quantum transport phenomena that are not limited by the ground state characteristics and have facilitated extensive explorations of quantum and topological interest in two- and three-dimensional materials. Here, in elemental metal Cr with two incommensurately superposed lattices of ions and a spin-density-wave ground state, we reveal that the phases of several low-frequency SdH oscillations in${\sigma }_{\mathit{xx}} \left({\rho }_{\mathit{xx}}\right)$and${\sigma }_{\mathit{yy}} \left({\rho }_{\mathit{yy}}\right)$are no longer identical but opposite. These relationships contrast with the SdH oscillations from normal cyclotron orbits that maintain identical phases between${\sigma }_{\mathit{xx}} \left({\rho }_{\mathit{xx}}\right)$and${\sigma }_{\mathit{yy}} \left({\rho }_{\mathit{yy}}\right)$ . We trace the origin of the low-frequency SdH oscillations to quantum interference effects arising from the incommensurate orbits of Cr’s superposed reciprocal lattices and explain the observed$\pi$-phase shift by the reconnection of anisotropic joint open and closed orbits.

    

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2. Extending superposed harmonic initial data to higher spin

   https://doi.org/10.1103/PhysRevD.103.084029  

   Ma, Sizheng ; Giesler, Matthew ; Scheel, Mark A. ; Varma, Vijay ( April 2021 , Physical Review D)

   null (Ed.)
3. Superposed Epoch Analyses of Electron‐Driven and Proton‐Driven Magnetic Dips

   https://doi.org/10.1029/2021GL094934  

   Zhu, Hui ; Chen, Lunjin ; Artemyev, Anton V. ; Zhang, Xiao‐Jia ; Breneman, A. W. ( November 2021 , Geophysical Research Letters)

   In this study, we statistically investigate the features of magnetic dips by constructing superposed epoch analysis on Van Allen Probe data. Based on the values of electron and proton plasma betas, we categorize dips into two types: electron‐dominant and proton‐dominant. The global distributions of dips are obtained. Superposed epoch analysis on two types reveals a correlation between the magnetic fluctuations and plasma betas. Moreover, the occurrences of butterfly pitch angle distributions of relativistic electrons driven by the magnetic dips are confirmed on a statistical basis. Our results reveal the statistical characteristics of magnetic dips and establish the relationship among the magnetic fluctuations and background plasma parameters, indicating the potentially important role of magnetic dips in the inner magnetosphere dynamics.

    

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4. Superposed metric for spinning black hole binaries approaching merger

   https://doi.org/10.1103/PhysRevD.104.044041  

   Combi, Luciano ; Armengol, Federico G. ; Campanelli, Manuela ; Ireland, Brennan ; Noble, Scott C. ; Nakano, Hiroyuki ; Bowen, Dennis ( August 2021 , Physical Review D)
5. Superposed Epoch Analysis of Dispersionless Particle Injections Inside Geosynchronous Orbit

   https://doi.org/10.1029/2021JA029546  

   Motoba, T. ; Ohtani, S. ; Gkioulidou, M. ; Ukhorskiy, A. Y. ; Lanzerotti, L. J. ; Claudepierre, S. G. ( July 2021 , Journal of Geophysical Research: Space Physics)

   Dispersionless injections, involving sudden, simultaneous flux enhancements of energetic particles over some broad range of energy, are a characteristic signature of the particles that are experiencing a significant acceleration and/or rapid inward transport at the leading edge of injections. We have statistically analyzed data from Van Allen Probes (also known as Radiation Belt Storm Probes [RBSP]) to reveal where the proton (H⁺) and electron (e^–) dispersionless injections occur preferentially inside geosynchronous orbit and how they develop depending on local magnetic field changes. By surveying measurements of RBSP during four tail seasons in 2012–2019, we have identified 171 dispersionless injection events. Most of the events, which are accompanied by local magnetic dipolarizations, occur in the dusk‐to‐midnight sector, regardless of particle species. Out of the selected 171 events, 75 events exhibit dispersionless injections of both H⁺and e^–, which occur within 2 min of each other. With only three exceptions, the both‐species injection events are further divided into two main subgroups: One is the H⁺preceding e^–events with a time offset of tens of seconds between H⁺and e^–, and the other the concurrent H⁺and e^–events without any time offset. Our superposed epoch results raise the intriguing possibility that the presence or absence of a pronounced negative dip in the local magnetic field ahead of the concurrent sharp dipolarization determines which of the two subgroups will occur. The difference between the two subgroups may be explained in terms of the dawn‐dusk asymmetry of localized diamagnetic perturbations ahead of a deeply penetrating dipolarization front.

    

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