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The discovery of atomic monolayer magnetic materials has stimulated intense research activities in the two-dimensional (2D) van der Waals (vdW) materials community. The field is growing rapidly and there has been a large class of 2D vdW magnetic compounds with unique properties, which provides an ideal platform to study magnetism in the atomically thin limit. In parallel, based on tunneling magnetoresistance and magneto-optical effect in 2D vdW magnets and their heterostructures, emerging concepts of spintronic and optoelectronic applications such as spin tunnel field-effect transistors and spin-filtering devices are explored. While the magnetic ground state has been extensively investigated, reliable characterization and control of spin dynamics play a crucial role in designing ultrafast spintronic devices. Ferromagnetic resonance (FMR) allows direct measurements of magnetic excitations, which provides insight into the key parameters of magnetic properties such as exchange interaction, magnetic anisotropy, gyromagnetic ratio, spin-orbit coupling, damping rate, and domain structure. In this review article, we present an overview of the essential progress in probing spin dynamics of 2D vdW magnets using FMR techniques. Given the dynamic nature of this field, we focus mainly on broadband FMR, optical FMR, and spin-torque FMR, and their applications in studying prototypical 2D vdW magnets. We conclude with the recent advances in laboratory- and synchrotron-based FMR techniques and their opportunities to broaden the horizon of research pathways into atomically thin magnets. 

The summertime surface ozone (O3) concentrations over Southeast Michigan (SEMI) often exceed 70 ppbv. However, the associated O3 formation regime is still not well known. In this study, we examined the chemical drivers of O3 exceedances in SEMI, based on the Michigan-Ontario Ozone Source Experiment (MOOSE) field campaign during the period of May 20 – June 30, 2021. We employed a zero-dimensional (0-D) box model, which was constrained by measurements of meteorology and trace gas concentrations during MOOSE. Our model simulations demonstrated that the formaldehyde to nitrogen dioxide ratio (HCHO/NO2) for the transition between the VOC- and NOx-limited O3 production regimes was 3.0 ± 0.3 (mean ± 1σ) in SEMI. The midday (12:00-16:00) averaged HCHO/NO2 ratio during MOOSE was 1.62 ± 1.03, suggesting that O3 production in SEMI was likely limited by VOC emissions. Our study has significant implications for air quality policy and the design of effective O3 pollution control strategies through ground-based HCHO/NO2 measurements and model simulations. 

Abstract This report is on the synthesis by electrospinning of multiferroic core-shell nanofibers of strontium hexaferrite and lead zirconate titanate or barium titanate and studies on magneto-electric (ME) coupling. Fibers with well-defined core–shell structures showed the order parameters in agreement with values for nanostructures. The strength of ME coupling measured by the magnetic field-induced polarization showed the fractional change in the remnant polarization as high as 21%. The ME voltage coefficient in H-assembled films showed the strong ME response for the zero magnetic bias field. Follow-up studies and potential avenues for enhancing the strength of ME coupling in the core–shell nanofibers are discussed. 

The effect of initial texture on cyclic deformation behavior of extruded ZK60 magnesium (Mg) alloy was experimentally investigated under strain‐controlled loading with the strain amplitudes at 4%, 1%, and 0.35%. The testing specimens were taken from extrusion direction (ED), transverse direction (TD), and a material precompressed to 9.4% along the ED (ED_−9.4%). At a high strain amplitude of 4%, the cyclic deformation modes of ED and ED_−9.4%specimens are similar, and they experience twinning exhaustion → slip and detwinning exhaustion → slip during each loading cycle. At a medium strain amplitude of 1%, twinning‐detwinning is involved in the cyclic deformation, but different deformation mechanisms were observed in the 3 different specimens. Partial twinning‐complete detwinning mode dominates the cyclic deformation in the ED specimen, while partial detwinning‐retwinning mode occurs in the ED_−9.4%specimen. For the TD specimen, both basal slip andtension twinning occur during cyclic deformation. At a low strain amplitude of 0.35%, dislocation slips dominate the deformation for the ED specimen with a few observable tension twins. For the ED_−9.4%specimen, initially twined texture increases the ductility of the material and enhances fatigue life as compared with the other 2 specimens.