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High-k turbulence (1 < kθρs < 5) spectrograms have been directly measured in density modulation experiments of the EAST tokamak using the collective Thomson scattering diagnostic system. Density-peaking modulation is achieved in Lower Hybrid Wave (LHW) modulation experiments, revealing that the broadband turbulence is sensitive to the power modulation of LHW and the concomitant variation of density-peaking. Additionally, the contributions of 2.45/4.6 GHz LHW to density peaking differ when Neutral Beam Injection (NBI) is on/off, displaying distinct responses of broadband turbulence in low/high frequency ranges. It is found by cross-coherence analysis that the phase angle is negative in cases without NBI, while in NBI cases it can be modulated from negative to positive, indicating a significant transition of radial turbulence propagation. These findings highlight the active control of density-peaking via auxiliary heating in tokamak plasmas and suggest the potential role of high-k turbulence in density-peaking modulation.

Antiferromagnetic (AFM) materials possess unique properties, such as rapid dynamic response, resistance to external magnetic disturbances, and the absence of a stray field. AFM materials are important members in the field of spintronics, and generating the spin current in AFM materials is one of the vital topics for AFM spintronics. The spin photovoltaic effect (SPVE) is the spin counterpart of the bulk photovoltaic effect (BPVE), where the photocurrent is spin-polarized. This effect can generate spin current in a contactless and ultra-fast way. Recently, SPVE has garnered significant interest due to its potential application in AFM spintronics and rich physical content. In this perspective, the mechanism of SPVE, including the relationship between SPVE and BPVE, and symmetry constraints are reviewed. We also provide an overview of recent progress on SPVE in AFM materials. This perspective also offers a viewpoint on this exciting area of research.

We investigated the hydraulic efficiency of spark-generated bubbles under conditions of different discharge polarities and different electrode numbers. A positive polarity discharge can generate a larger spark-induced bubble than a negative polarity discharge generated using the same electrical and electrode parameters. The hydraulic efficiency of both the positive and negative polarity discharges decreases with the increasing number of electrodes. Increasing the number of electrodes leads to faster energy injection times and higher average powers. We found that the hydraulic efficiency increases when energy injection time increases but that it decreases when the average power increases. When the energy injection time is longer than 100 µs and the average power is less than 100 kW, hydraulic efficiencies of more than 15% and 10% were realized for the positive and negative polarity discharges, respectively. These results indicate that longer energy injection times will be helpful in gaining higher hydraulic efficiency for these bubbles.

By combining first-principles calculations and symmetry arguments, we propose that the half-metallic phase of K _2 Cr _8 O _16 presents ferromagnetic Weyl fermions. In particular, K _2 Cr _8 O _16 possesses two pairs of Weyl nodes, which originate from two groups of nodal lines connected by the mirror reflection symmetry. We show that the non-trivial topological properties of K _2 Cr _8 O _16 come from the partially occupied t _2g states of Cr, and we also demonstrate that such exotic topological feature is robust. The topological surface states and corresponding Fermi arcs are revealed. As K _2 Cr _8 O _16 is a realistic and widely studied material, our results suggest that K _2 Cr _8 O _16 is an ideal candidate for studying ferromagnetic Weyl fermions. In addition, K _2 Cr _8 O _16 possesses several interesting phenomena, such as the co-existence of charge density wave and Weyl fermions, even pairs of FM Weyl points, and tunable distribution of Weyl points, which will attract intensive attentions in this field.

The effects of the waveguide layer on the band structure of Rayleigh waves are studied in this work based on a one-dimensional acoustic superlattice lithium niobate substrate coated with a waveguide layer. The present phononic structure is formed by the periodic domain-inverted single crystal that is the Z-cut lithium niobate substrate with a waveguide layer on the upper surface. The plane wave expansion method (PWE) is adopted to determine the band gap behavior of the phononic structure and validated by the finite element method (FEM). The FEM is also used to investigate the transmission of Rayleigh waves in the phononic structure with the interdigital transducers by means of the commercial package COMSOL. The results show that, although there is a homogeneous waveguide layer on the surface, the band gap of Rayleigh waves still exist. It is also found that increasing the thickness of the waveguide layer, the band width narrows and the band structure shifts to lower frequency. The present approach can be taken as an efficient tool in designing of phononic structures with waveguide layer.

Global climate variability affects important local hydro-meteorological variables like precipitation and temperature. The Southern Oscillation (SO) is an easily quantifiable major driving force that gives impact on regional and local climate. The relationships between SO and local climate variation are, however, characterized by strongly nonlinear processes. Due to this, teleconnections between global-scale hydro-meteorological variables and local climate are not well understood. In this paper, we suggest to study these processes in terms of nonlinear dynamics. Consequently, the nonlinear dynamic relationship between the Southern Oscillation Index (SOI), precipitation, and temperature in Fukuoka, Japan, is investigated using a nonlinear multivariable approach. This approach is based on the joint variation of these variables in the phase space. The joint phase-space variation of SOI, precipitation, and temperature is studied with the primary objective to obtain a better understanding of the dynamical evolution of local hydro-meteorological variables affected by global atmospheric-oceanic phenomena. The results from the analyses display rather clear low-order phase space trajectories when treating the time series individually. However, when plotting phase space trajectories for several time series jointly, complicated higher-order nonlinear relationships emerge between the variables. Consequently, simple data-driven prediction techniques utilizing phase-space characteristics of individual time series may prove successful. On the other hand, since either the time series are too short and/or the phase-space properties are too complex when analysing several variables jointly, it may be difficult to use multivariable statistical prediction techniques for the present investigated variables. In any case, it is essential to further pursue studies regarding links between the SOI and observed local climatic and other geophysical variables even if these links are not fully understood in physical terms.

We report on the tunable photovoltaic effect of self-doped single-crystal SrTiO3 (STO), a prototypical perovskite-structured complex oxide, and evaluate its performance in Schottky junction solar cells. The photovaltaic characteristics of vacuum-reduced STO single crystals are dictated by a thin surface layer with electrons donated by oxygen vacancies. Under UV illumination, a photovoltage of 1.1 V is observed in the as-received STO single crystal, while the sample reduced at 750 °C presents the highest incident photon to carrier conversion efficiency. Furthermore, in the STO/Pt Schottky junction, a power conversion efficiency of 0.88% was achieved under standard AM 1.5 illumination at room temperature. This work establishes STO as a high-mobility photovoltaic semiconductor with potential of integration in self-powered oxide electronics.