A new monocrystalline 2D high-κ dielectric
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Geochemistry of lithospheric aqueous fluids modified by nanoconfinement
Water is a principal component of Earth’s fluids, and its interaction with rocks governs lithospheric geochemical and geodynamic processes. Water–rock interactions are crucial in societally relevant resource management, including subsurface extraction and storage of energy, the deep carbon cycle and generating critical metal deposits. The prevailing view is that fluids navigate through the lithosphere without being influenced by the distinct properties that arise from matter confined at the nanoscale. Here we use electron microscopy and neutron scattering data to show that a diverse range of lithospheric rocks, including sandstones, peridotites and serpentinites, consistently show nanoporosity, predominantly with pore sizes < 100 nanometres. Using molecular dynamics simulations, we demonstrate that water’s dielectric permittivity—a fundamental property that governs its geochemical behaviour—diverges in nanoconfinement from its bulk counterpart under conditions ranging from ambient to extremes of 700 °C and 5 GPa. Our geochemical simulations suggest that changes in water permittivity due to confinement will decrease mineral solubility, a process that is not currently considered in models of fluid–rock interactions. Given that permittivity is also intimately linked to ion speciation, pore-size-dependent properties should be expected to exert a primary influence on rock reactivity and the geochemical evolution of fluids during fluid–rock interactions.
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Flexible electromagnetic metamaterials are a potential candidate for the ideal material for electromagnetic control due to their unique physical properties and structure. Flexible electromagnetic metamaterials can be designed to exhibit specific responses to electromagnetic waves within a particular frequency range. Research shows that flexible electromagnetic metamaterials exhibit significant electromagnetic control characteristics in microwave, terahertz, infrared and other frequency bands. It has a wide range of applications in the fields of electromagnetic wave absorption and stealth, antennas and microwave devices, communication information and other fields. In this review, the currently popular fabrication methods of flexible electromagnetic metamaterials are first summarized, highlighting the electromagnetic modulation capability in different frequency bands. Then, the applications of flexible electromagnetic metamaterials in four aspects, namely electromagnetic stealth, temperature modulation, electromagnetic shielding, and wearable sensors, are elaborated and summarized in detail. In addition, this review also discusses the shortcomings and limitations of flexible electromagnetic metamaterials for electromagnetic control. Finally, the conclusion and perspective of the electromagnetic properties of flexible electromagnetic metamaterials are presented.
Boron nitride for applications in microelectronics
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Controlling Coulomb correlations and fine structure of quasi-one-dimensional excitons by magnetic order
Many surprising properties of quantum materials result from Coulomb correlations defining electronic quasiparticles and their interaction chains. In van der Waals layered crystals, enhanced correlations have been tailored in reduced dimensions, enabling excitons with giant binding energies and emergent phases including ferroelectric, ferromagnetic and multiferroic orders. Yet, correlation design has primarily relied on structural engineering. Here we present quantitative experiment–theory proof that excitonic correlations can be switched through magnetic order. By probing internal Rydberg-like transitions of excitons in the magnetic semiconductor CrSBr, we reveal their binding energy and a dramatic anisotropy of their quasi-one-dimensional orbitals manifesting in strong fine-structure splitting. We switch the internal structure from strongly bound, monolayer-localized states to weakly bound, interlayer-delocalized states by pushing the system from antiferromagnetic to paramagnetic phases. Our analysis connects this transition to the exciton’s spin-controlled effective quantum confinement, supported by the exciton’s dynamics. In future applications, excitons or even condensates may be interfaced with spintronics; extrinsically switchable Coulomb correlations could shape phase transitions on demand.
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