Controlling the thermal energy of lattice vibrations separately from electrons is vital to many applications including electronic devices and thermoelectric energy conversion. To remove heat without shorting electrical connections, heat must be carried in the lattice of electrical insulators. Phonons are limited to the speed of sound, which, compared to the speed of electronic processes, puts a fundamental constraint on thermal management. Here we report a supersonic channel for the propagation of lattice energy in the technologically promising piezoelectric mineral fresnoite (BaTiSiO) using neutron scattering. Lattice energy propagates 2.8-4.3 times the speed of sound in the form of phasons, which are caused by an incommensurate modulation in the flexible framework structure of fresnoite. The phasons enhance the thermal conductivity by 20% at room temperature and carry lattice-energy signals at speeds beyond the limits of phonons.
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http://dx.doi.org/10.1038/s41467-018-04229-1 | DOI Listing |
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January 2025
State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou, 730000, China.
Polymer composite materials encounter considerable challenges in sustaining superior tribological properties at high rotational speeds. Inspired by the microstructure of dragonfly wings, a novel thermally stable and ambient pressure curing poly(urea-imide) resin (PURI) with excellent tribological properties has been eco-friendly synthesis using bio-based greener solvents. Furthermore, The PURI composites enhanced with polyether ether ketone (PEEK) and Polytetrafluoroethylene (PTFE) blended fabrics demonstrate excellent mechanical, with tensile strengths exceeding 175 MPa.
View Article and Find Full Text PDFJ Phys Chem Lett
January 2025
DST Unit of Nanoscience (DST UNS) and Thematic Unit of Excellence (TUE), Department of Chemistry, Indian Institute of Technology Madras, Chennai 600036, India.
Clathrate hydrates (CHs) are believed to exist in cold regions of space, such as comets and icy moons. While spectroscopic studies have explored their formation under similar laboratory conditions, direct structural characterization using diffraction techniques has remained elusive. We present the first electron diffraction study of tetrahydrofuran (THF) and 1,3-dioxolane (DIOX) CHs in the form of nanometer-thin ice films under an ultrahigh vacuum at cryogenic temperatures.
View Article and Find Full Text PDFAdv Mater
January 2025
Center for Hybrid Organic-Inorganic Semiconductors for Energy, Golden, Colorado, 80401, USA.
Recent activity in the area of chiroptical phenomena has been focused on the connection between structural asymmetry, electron spin configuration and light/matter interactions in chiral semiconductors. In these systems, spin-splitting phenomena emerge due to inversion symmetry breaking and the presence of extended electronic states, yet the connection to chiroptical phenomena is lacking. Here, we develop an analytical effective mass model of chiral excitons, parameterized by density functional theory.
View Article and Find Full Text PDFNature
January 2025
Department of Physics, The Hong Kong University of Science and Technology, Kowloon, Hong Kong, China.
The concept of non-Hermiticity has expanded the understanding of band topology, leading to the emergence of counter-intuitive phenomena. An example is the non-Hermitian skin effect (NHSE), which involves the concentration of eigenstates at the boundary. However, despite the potential insights that can be gained from high-dimensional non-Hermitian quantum systems in areas such as curved space, high-order topological phases and black holes, the realization of this effect in high dimensions remains unexplored.
View Article and Find Full Text PDFNature
January 2025
Department of Chemistry, National University of Singapore, Singapore, Singapore.
Topological design of π electrons in zigzag-edged graphene nanoribbons (ZGNRs) leads to a wealth of magnetic quantum phenomena and exotic quantum phases. Symmetric ZGNRs typically show antiferromagnetically coupled spin-ordered edge states. Eliminating cross-edge magnetic coupling in ZGNRs not only enables the realization of a class of ferromagnetic quantum spin chains, enabling the exploration of quantum spin physics and entanglement of multiple qubits in the one-dimensional limit, but also establishes a long-sought-after carbon-based ferromagnetic transport channel, pivotal for ultimate scaling of GNR-based quantum electronics.
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