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Long viewed as passive elements, antiferromagnetic materials have emerged as promising candidates for spintronic devices due to their insensitivity to external fields and potential for high-speed switching. Recent work exploiting spin and orbital effects has identified ways to electrically control and probe the spins in metallic antiferromagnets, especially in non-collinear or non-centrosymmetric spin structures. The rare-earth nickelate NdNiO3is known to be a non-collinear antiferromagnet in which the onset of antiferromagnetic ordering is concomitant with a transition to an insulating state. Here we find that for low electron doping, the magnetic order on the nickel site is preserved, whereas electronically, a new metallic phase is induced. We show that this metallic phase has a Fermi surface that is mostly gapped by an electronic reconstruction driven by bond disproportionation. Furthermore, we demonstrate the ability to write to and read from the spin structure via a large zero-field planar Hall effect. Our results expand the already rich phase diagram of rare-earth nickelates and may enable spintronics applications in this family of correlated oxides.

Nanophotonic materials offer spectral and directional control over thermal emission, but in high-temperature oxidizing environments, their stability remains low. This limits their applications in technologies such as solid-state energy conversion and thermal barrier coatings. Here we show an epitaxial heterostructure of perovskite BaZr0.5Hf0.5O3(BZHO) and rocksalt MgO that is stable up to 1,100 °C in air. The heterostructure exhibits coherent atomic registry and clearly separated refractive-index-mismatched layers after prolonged exposure to this extreme environment. The immiscibility of the two materials is corroborated by the high formation energy of substitutional defects from density functional theory calculations. The epitaxy of immiscible refractory oxides is, therefore, an effective method to avoid prevalent thermal instabilities in nanophotonic materials, such as grain-growth degradation, interlayer mixing and oxidation. As a functional example, a BZHO/MgO photonic crystal is implemented as a filter to suppress long-wavelength thermal emission from the leading bulk selective emitter and effectively raise its cutoff energy by 20%, which can produce a corresponding gain in the efficiency of mobile thermophotovoltaic systems. Beyond BZHO/MgO, computational screening shows that hundreds of potential cubic oxide pairs fit the design principles of immiscible refractory photonics. Extending the concept to other material systems could enable further breakthroughs in a wide range of photonic and energy conversion applications.

Rashba spin current generation emerges in heterostructures of ferromagnets and transition metal dichalcogenides (TMDs) due to an interface polarization and associated inversion symmetry breaking. Recent work exploring the synthesis and transfer of epitaxial films on the top of low layer count 2D materials reveals that atomic potentials from the underlying substrate interface are not completely screened. The extension of this transparency effect to other interfacial phenomena, such as the Rashba effect and associated spin torques, has not yet been demonstrated. Here, we report enhanced spin transfer torques from the Rashba spin current in heterostructures of permalloy (Py) and WSe2. We show that insertion of up to two monolayers of WSe2enhances the spin transfer torques in a Rashba system by up to 3×, without changing the fieldlike Rashba spin–orbit torque (SOT), a measure of interface polarization. Our results indicate that low layer count TMD films can be used as an interfacial “scattering promoter” in heterostructure interfaces without quenching the original polarization.

Since the discovery of high-temperature superconductivity in copper oxide materials1, there have been sustained efforts to both understand the origins of this phase and discover new cuprate-like superconducting materials2. One prime materials platform has been the rare-earth nickelates and, indeed, superconductivity was recently discovered in the doped compound Nd0.8Sr0.2NiO2(ref. 3). Undoped NdNiO2belongs to a series of layered square-planar nickelates with chemical formula Ndn+1NinO2n+2and is known as the ‘infinite-layer’ (n= ∞) nickelate. Here we report the synthesis of the quintuple-layer (n= 5) member of this series, Nd6Ni5O12, in which optimal cuprate-like electron filling (d8.8) is achieved without chemical doping. We observe a superconducting transition beginning at ~13 K. Electronic structure calculations, in tandem with magnetoresistive and spectroscopic measurements, suggest that Nd6Ni5O12interpolates between cuprate-like and infinite-layer nickelate-like behaviour. In engineering a distinct superconducting nickelate, we identify the square-planar nickelates as a new family of superconductors that can be tuned via both doping and dimensionality.

Abstract: With the explosion of Internet traffic, the rise of large data centers, and smart technologies on the horizon, forecasts of the global energy consumption from information, and communications technologies are expected to rise from ~ 8% in 2020 to ~ 21% in 2030. The future demand will challenge the supply of electricity and has technology makers looking for ways to improve the efficiency of information and communication devices. In recent years, advances in magnetoelectric and multiferroic materials now provide the basis for nonvolatile spin-based logic and memory elements that have a projected energy efficiency orders of magnitude larger than the complementary metal-oxide semiconductor transistor. The possibilities are exciting, yet significant challenges remain. This article summarizes key materials, recent advancements, and current challenges in electric-field-controlled magnetism for realizing these potentially transformational devices. A perspective and potential considerations are given. Graphic abstract: With the explosion of Internet traffic, the rise of large data centers, and smart technologies on the horizon, forecasts of the global energy consumption from information and communications technologies are expected to rise from ~8% in 2020 to ~21% in 2030. The future demand will challenge the supply of electricity and has technology makers looking for ways to improve the efficiency of information and communication devices. In recent years, advances in magnetoelectric and multiferroic materials now provide the basis for nonvolatile spin-based logic and memory elements that have a projected energy efficiency orders of magnitude larger than the CMOS (Complementary Metal Oxide Semiconductor) transistor. The possibilities are exciting, yet significant challenges remain. This article summarizes key materials, recent advancements, and current challenges in electric-field controlled magnetism for realizing these potentially transformational devices. A perspective and potential considerations are given.

A single-phase multiferroic material is constructed, in which ferroelectricity and strong magnetic ordering are coupled near room temperature, enabling direct electric-field control of magnetism.

Solid-state hydrogen gating of a ferrimagnetic metal enables independent reversal of Néel and magnetization vectors by an electric field.

The effect of partial substitution of titanium for cobalt on 3b sites in Li1+z(NixMnxCo1-2x-yTiy)O2 (x = 1/3, 0.4) cathode materials (NMCs) has been investigated for this study. Materials were prepared by glycine-nitrate combustion and co-precipitation methods and solid solutions were observed over a narrow substitution range limited to below about y = 0.07 for both the x = 1/3 and x = 0.4 series, although this depended on the synthesis technique. Increased discharge capacities, lower first cycle inefficiencies and better cycling behavior were observed for several of the Ti-substituted compositions in electrochemical cells. The improved first cycle efficiencies allow higher discharge capacities to be obtained between normal voltage limits, which partly explain the observations. Results from synchrotron X-ray diffraction also indicate that Ti substitution leads to a decreased cell volume change during deintercalation of lithium, which contributes to the improved cycling performance. Magnetic measurements suggest that reduction of some Mn4+ to Mn3+ compensates for the aliovalent substitution in as-made lithium-stoichiometric materials.

Certain materials contain both electric dipoles and magnetic moments. An experiment demonstrates that these properties can be coupled in previously unrecognized ways, leading to advanced functionality. Domain patterns inverted by a uniform magnetic field.