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Abstract Lunar paleomagnetic studies have identified multidomain metallic Fe–Ni alloys as the dominant magnetic contributors in mare basalts. Here, we explore the low‐temperature magnetic behavior of standard samples for a suite of opaque minerals that occur within mare basalts (single‐domain and multidomain Fe, wüstite, ulvöspinel, iron chromite, ilmenite, and troilite). We compare the observed low‐temperature behaviors to those of several Apollo mare basalt samples (10003, 10044, 10020, 10069, 10071, 12009, 12022, 15597). Notable magnetic transitions were detected at 30 K (ilmenite), 60–80 K (chromite, troilite), and 100–125 K (ulvöspinel, chromite). We also investigated the effects of low‐temperature cycling on mare basalt remanence and observed that only grains with coercivities 20–40 mT were cleaned. This suggests a minimal impact of diurnal temperature cycling at the lunar surface on the retrieved lunar paleointensity values. Using comprehensive electron microscopy techniques, including scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), wavelength dispersive spectroscopy (WDS), x‐ray diffraction, and transmission electron microscopy (TEM), we further examined magnetic phases within four Apollo 11 mare basalt samples. Our findings revealed the presence of Fe grains (one to 10 μm in diameter) associated with troilite contain sub‐grains ranging in size from tens to hundreds of nanometers in some samples. These grains, which fall within the single‐domain to multi‐domain range as observed in their first‐order reversal curves, might have the potential to retain high coercivity components and thereby effectively record an ancient dynamo field. 

Self-discharge and chemically induced mechanical effects degrade calendar and cycle life in intercalation-based electrochromic and electrochemical energy storage devices. In rechargeable lithium-ion batteries, self-discharge in cathodes causes voltage and capacity loss over time. The prevailing self-discharge model centers on the diffusion of lithium ions from the electrolyte into the cathode. We demonstrate an alternative pathway, where hydrogenation of layered transition metal oxide cathodes induces self-discharge through hydrogen transfer from carbonate solvents to delithiated oxides. In self-discharged cathodes, we further observe opposing proton and lithium ion concentration gradients, which contribute to chemical and structural heterogeneities within delithiated cathodes, accelerating degradation. Hydrogenation occurring in delithiated cathodes may affect the chemo-mechanical coupling of layered cathodes as well as the calendar life of lithium-ion batteries. 

Abstract Ultra-thin films of low damping ferromagnetic insulators with perpendicular magnetic anisotropy have been identified as critical to advancing spin-based electronics by significantly reducing the threshold for current-induced magnetization switching while enabling new types of hybrid structures or devices. Here, we have developed a new class of ultra-thin spinel structure Li_0.5Al_1.0Fe_1.5O₄(LAFO) films on MgGa₂O₄(MGO) substrates with: 1) perpendicular magnetic anisotropy; 2) low magnetic damping and 3) the absence of degraded or magnetic dead layers. These films have been integrated with epitaxial Pt spin source layers to demonstrate record low magnetization switching currents and high spin-orbit torque efficiencies. These LAFO films on MGO thus combine all of the desirable properties of ferromagnetic insulators with perpendicular magnetic anisotropy, opening new possibilities for spin based electronics.