Explore the vast range of titles available.

Dielectric capacitors with high energy storage density ( W rec ) and efficiency ( η ) are in great demand for high/pulsed power electronic systems, but the state-of-the-art lead-free dielectric materials are facing the challenge of increasing one parameter at the cost of the other. Herein, we report that high W rec of 6.3 J cm -3 with η of 90% can be simultaneously achieved by constructing a room temperature M2–M3 phase boundary in (1- x )AgNbO 3 - x AgTaO 3 solid solution system. The designed material exhibits high energy storage stability over a wide temperature range of 20–150 °C and excellent cycling reliability up to 10 6 cycles. All these merits achieved in the studied solid solution are attributed to the unique relaxor antiferroelectric features relevant to the local structure heterogeneity and antiferroelectric ordering, being confirmed by scanning transmission electron microscopy and synchrotron X-ray diffraction. This work provides a good paradigm for developing new lead-free dielectrics for high-power energy storage applications. Dielectric capacitors are widely used in electronic systems but they possess inferior energy density in comparison with other electrochemical energy storage. Here, the authors construct a diffused phase boundary to simultaneously achieve high energy storage density and efficiency in AgNbO 3 antiferroelectrics.

The latest discovery of high temperature superconductivity near 80 K in La 3 Ni 2 O 7 under high pressure has attracted much attention. Many proposals are put forth to understand the origin of superconductivity. The determination of electronic structures is a prerequisite to establish theories to understand superconductivity in nickelates but is still lacking. Here we report our direct measurement of the electronic structures of La 3 Ni 2 O 7 by high-resolution angle-resolved photoemission spectroscopy. The Fermi surface and band structures of La 3 Ni 2 O 7 are observed and compared with the band structure calculations. Strong electron correlations are revealed which are orbital- and momentum-dependent. A flat band is formed from the Ni-3d z 2 orbitals around the zone corner which is ~ 50 meV below the Fermi level and exhibits the strongest electron correlation. In many theoretical proposals, this band is expected to play the dominant role in generating superconductivity in La 3 Ni 2 O 7 . Our observations provide key experimental information to understand the electronic structure and origin of high temperature superconductivity in La 3 Ni 2 O 7 . Recently, superconductivity near 80 K was observed in La3Ni2O7 under high pressure, but the mechanism is debated. Here the authors report angle-resolved photoemission spectroscopy measurements under ambient pressure, revealing flat bands with strong electronic correlations that could be linked to superconductivity.

Improving the absorption of electromagnetic waves at low-frequency bands (2-8 GHz) is crucial for the increasing electromagnetic (EM) pollution brought about by the innovation of the fifth generation (5G) communication technology. However, the poor impedance matching and intrinsic attenuation of material in low-frequency bands hinders the development of low-frequency electromagnetic wave absorbing (EMWA) materials. Here we propose an interface-induced dual-pinning mechanism and establish a magnetoelectric bias interface by constructing bilayer core-shell structures of NiFe 2 O 4 (NFO)@BiFeO 3 (BFO)@polypyrrole (PPy). Such heterogeneous interface could induce distinct magnetic pinning of the magnetic moment in the ferromagnetic NFO and dielectric pinning of the dipole rotation in PPy. The establishment of the dual-pinning effect resulted in optimized impedance and enhanced attenuation at low-frequency bands, leading to better EMWA performance. The minimum reflection loss (RL min ) at thickness of 4.43 mm reaches -65.30 dB (the optimal absorption efficiency of 99.99997%), and the effective absorption bandwidth (EAB) can almost cover C-band (4.72 ~ 7.04 GHz) with low filling of 15.0 wt.%. This work proposes a mechanism to optimize low-frequency impedance matching with electromagnetic wave (EMW) loss and pave an avenue for the research of high-performance low-frequency absorbers. This paper proposes a dual-pinning mechanism induced by a magneto-electric bias interface and uses it to designs a double-layer core-shell structure, demonstrating that the mechanism improves electromagnetic wave absorption in the low-frequency bands.

When electric conductors differ from their mirror image, unusual chiral transport coefficients appear that are forbidden in achiral metals, such as a non-linear electric response known as electronic magnetochiral anisotropy (eMChA) 1 – 6 . Although chiral transport signatures are allowed by symmetry in many conductors without a centre of inversion, they reach appreciable levels only in rare cases in which an exceptionally strong chiral coupling to the itinerant electrons is present. So far, observations of chiral transport have been limited to materials in which the atomic positions strongly break mirror symmetries. Here, we report chiral transport in the centrosymmetric layered kagome metal CsV 3 Sb 5 observed via second-harmonic generation under an in-plane magnetic field. The eMChA signal becomes significant only at temperatures below T ′ ≈ 35 K, deep within the charge-ordered state of CsV 3 Sb 5 ( T CDW  ≈ 94 K). This temperature dependence reveals a direct correspondence between electronic chirality, unidirectional charge order 7 and spontaneous time-reversal symmetry breaking due to putative orbital loop currents 8 – 10 . We show that the chirality is set by the out-of-plane field component and that a transition from left- to right-handed transport can be induced by changing the field sign. CsV 3 Sb 5 is the first material in which strong chiral transport can be controlled and switched by small magnetic field changes, in stark contrast to structurally chiral materials, which is a prerequisite for applications in chiral electronics. Change of chirality from left- to right-handed transport in the layered kagome metal CsV 3 Sb 5 can be controlled by small magnetic field changes, a required feature for chiral electronic applications.

In the presence of a large perpendicular electric field, Bernal-stacked bilayer graphene (BLG) features several broken-symmetry metallic phases 1 – 3 as well as magnetic-field-induced superconductivity 1 . The superconducting state is quite fragile, however, appearing only in a narrow window of density and with a maximum critical temperature T c  ≈ 30 mK. Here we show that placing monolayer tungsten diselenide (WSe 2 ) on BLG promotes Cooper pairing to an extraordinary degree: superconductivity appears at zero magnetic field, exhibits an order of magnitude enhancement in T c and occurs over a density range that is wider by a factor of eight. By mapping quantum oscillations in BLG–WSe 2 as a function of electric field and doping, we establish that superconductivity emerges throughout a region for which the normal state is polarized, with two out of four spin-valley flavours predominantly populated. In-plane magnetic field measurements further reveal that superconductivity in BLG–WSe 2 can exhibit striking dependence of the critical field on doping, with the Chandrasekhar–Clogston (Pauli) limit roughly obeyed on one end of the superconducting dome, yet sharply violated on the other. Moreover, the superconductivity arises only for perpendicular electric fields that push BLG hole wavefunctions towards WSe 2 , indicating that proximity-induced (Ising) spin–orbit coupling plays a key role in stabilizing the pairing. Our results pave the way for engineering robust, highly tunable and ultra-clean graphene-based superconductors. Placing monolayer tungsten diselenide on Bernal-stacked bilayer graphene promotes enhanced superconductivity, indicating that proximity-induced spin–orbit coupling plays a key role in stabilizing the pairing, paving the way for engineering tunable, ultra-clean graphene-based superconductors.

Although historically materials discovery has been driven by a laborious trial-and-error process, knowledge-driven materials design can now be enabled by the rational combination of Machine Learning methods and materials databases. Here, data from the AFLOW repository for ab initio calculations is combined with Quantitative Materials Structure-Property Relationship models to predict important properties: metal/insulator classification, band gap energy, bulk/shear moduli, Debye temperature and heat capacities. The prediction’s accuracy compares well with the quality of the training data for virtually any stoichiometric inorganic crystalline material, reciprocating the available thermomechanical experimental data. The universality of the approach is attributed to the construction of the descriptors: Property-Labelled Materials Fragments. The representations require only minimal structural input allowing straightforward implementations of simple heuristic design rules. Machine learning methods can be useful for materials discovery; however certain properties remain difficult to predict. Here, the authors present a universal machine learning approach for modelling the properties of inorganic crystals, which is validated for eight electronic and thermomechanical properties.

The recently discovered layered kagome metals AV 3 Sb 5 (A = K, Rb, Cs) exhibit diverse correlated phenomena, which are intertwined with a topological electronic structure with multiple van Hove singularities (VHSs) in the vicinity of the Fermi level. As the VHSs with their large density of states enhance correlation effects, it is of crucial importance to determine their nature and properties. Here, we combine polarization-dependent angle-resolved photoemission spectroscopy with density functional theory to directly reveal the sublattice properties of 3d -orbital VHSs in CsV 3 Sb 5 . Four VHSs are identified around the M point and three of them are close to the Fermi level, with two having sublattice-pure and one sublattice-mixed nature. Remarkably, the VHS just below the Fermi level displays an extremely flat dispersion along MK, establishing the experimental discovery of higher-order VHS. The characteristic intensity modulation of Dirac cones around K further demonstrates the sublattice interference embedded in the kagome Fermiology. The crucial insights into the electronic structure, revealed by our work, provide a solid starting point for the understanding of the intriguing correlation phenomena in the kagome metals AV 3 Sb 5 . Predictions suggest enhanced correlation effect due to multiple van Hove singularities (VHS) in the vicinity of the Fermi level in the recently discovered A V 3 Sb 5 kagome metals. Here the authors identify three VHSs close to the Fermi level with diverse sublattice characters in CsV 3 Sb 5 , and one of them shows flat dispersion suggesting the higher-order nature.

The discovery of superconductivity with a critical temperature of about 80 K in La 3 Ni 2 O 7 single crystals under pressure has received enormous attention. La 3 Ni 2 O 7 is not superconducting under ambient pressure but exhibits a transition at T   ∗  ≃ 115 K. Understanding the electronic correlations and charge dynamics is an important step towards the origin of superconductivity and other instabilities. Here, our optical study shows that La 3 Ni 2 O 7 features strong electronic correlations which significantly reduce the electron’s kinetic energy and place this system in the proximity of the Mott phase. The low-frequency optical conductivity reveals two Drude components arising from multiple bands at the Fermi level. The transition at T   ∗ removes the Drude component exhibiting non-Fermi liquid behavior, whereas the one with Fermi-liquid behavior is barely affected. These observations in combination with theoretical results suggest that the Fermi surface dominated by the Ni- d 3 z 2 − r 2 orbital is removed due to the transition at T   ∗ . Our experimental results provide pivotal information for understanding the transition at T   ∗ and superconductivity in La 3 Ni 2 O 7 . The bilayer nickelate La 3 Ni 2 O 7 was recently shown to be superconducting at high-pressure. Here the authors reveal strong electronic correlations and the opening of a partial gap, providing key information for understanding the nature of the density-wavelike transition at ambient pressure and superconductivity in this compound.

Materials harbouring exotic quasiparticles, such as massless Dirac and Weyl fermions, have garnered much attention from physics and material science communities due to their exceptional physical properties such as ultra-high mobility and extremely large magnetoresistances. Here, we show that the highly stable, non-toxic and earth-abundant material, ZrSiS, has an electronic band structure that hosts several Dirac cones that form a Fermi surface with a diamond-shaped line of Dirac nodes. We also show that the square Si lattice in ZrSiS is an excellent template for realizing new types of two-dimensional Dirac cones recently predicted by Young and Kane. Finally, we find that the energy range of the linearly dispersed bands is as high as 2 eV above and below the Fermi level; much larger than of other known Dirac materials. This makes ZrSiS a very promising candidate to study Dirac electrons, as well as the properties of lines of Dirac nodes. The family of topological materials has been growing rapidly but most members bare limitations hindering the study of exotic behaviour of topological particles. Here, Schoop et al . report a Fermi surface with a diamond-shaped line of Dirac nodes in ZrSiS, providing a promising candidate for studying two-dimensional Dirac fermions.

Twisted bilayer graphene with a twist angle of around 1.1° features a pair of isolated flat electronic bands and forms a platform for investigating strongly correlated electrons. Here, we use scanning tunnelling microscopy to probe the local properties of highly tunable twisted bilayer graphene devices and show that the flat bands deform when aligned with the Fermi level. When the bands are half-filled, we observe the development of gaps originating from correlated insulating states. Near charge neutrality, we find a previously unidentified correlated regime featuring an enhanced splitting of the flat bands. We describe this within a microscopic model that predicts a strong tendency towards nematic ordering. Our results provide insights into symmetry-breaking correlation effects and highlight the importance of electronic interactions for all filling fractions in twisted bilayer graphene.