Highlights
Lorentz Ptychography for high-resolution, high sensitivity magnetic imaging
The study establishes a quantitative, high-resolution magnetic microscopy technique that can reveal nanoscale spin textures, especially magnetization discontinuities and topological defects in nanomagnets. The technique’s high-dose efficiency should also make it well suited for the exploration of magnetic textures in electron radiation-sensitive materials such as organic or molecular magnets.
Realizing a New Rutile Substrate for Epitaxial Film Growth
Here, a team from the University of Michigan came to PARADIM to grow single crystals of rutile-GeO2 motivated by their recent discovery of this new semiconductor—with an ultra-high band gap (4.64 eV), high mobility, high heat conductivity, and desired dopability.
Giant Pyroelectric Effect
Here, researchers from RPI came to PARADIM to characterize three model pyroelectric materials whose bonding character varies from a van der Waals material (In2Se3), to a quasi-van der Waals material (CsBiNb2O7), to an ionic/covalent material (ZnO).
Engineering Quantum Fabrics with Arbitrary Periodicities
This advance points to a new approach in engineering designer quantum fabrics with arbitrary periodicities, through the coupling of a third layer to an existing moiré heterostructure.
The Dawn of a New Generation of High-Brightness Electron Sources
The ultimate performance of some of the most powerful characterization tools including x-ray free electron lasers, ultrafast electron microscopes, and particle accelerators are determined by the ability of their electron sources to emit electrons. This small, yet vital element of these multimillion to multibillion dollar systems, has the potential to be improved greatly; the performance of commonly used electron sources pales in comparison to the theoretical limit due to roughness, disorder, and polycrystallinity. The path to maximally efficient electron sources is thus believed to lie with single-crystal films, where the smoothness, homogeneity, and termination can be controlled at the atomic level. Unfortunately, the most desired materials for electron sources contain highly reactive species like cesium, which has stymied the preparation of single-crystal films of these desired electron sources—until now.
Metallicity of Ultrathin SrIrO3/SrRuO3 Heterostructures
Ultrathin quantum materials present a unique platform for the control of electronic, magnetic, and topological properties. A commonly observed phenomenon in many ultrathin quantum materials is that an undesired crossover from a metallic to insulating state occurs below a critical thickness. This presents a potential challenge for realizing ultrathin heterostructures of quantum materials when metallic properties are desired.
Robotic Assembly of Quantum Fabrics from Atomically Thin Layers
Quantum fabrics offer novel electronic, magnetic, or topological textures with functionalities that do not exist in bulk and could play an important role in future quantum technologies. Quantum fabrics are created by weaving together "threads" with different properties, such as superconductivity or magnetism. One method to make them is the atomically precise assembly of layered two-dimensional Van der Waals (vdW) materials. This assembly has traditionally been accomplished using artisan methods from micromechanical exfoliated flakes, but such fabrication is not compatible with scalable and rapid manufacturing.
Polytype Engineering—A new Route to Accessing 2D Quantum States
Charge density waves (CDW) are an emergent periodic modulation of the electron density that permeates crystals with strong electron-lattice coupling. TaS:2: and TaSe:x:S:2-x: host several charge density wave states that spontaneously break crystal symmetries, mediate metal-insulator transitions, and compete with superconductivity. These quantum states are promising candidates for novel devices, efficient ultrafast nonvolatile switching, and suggest elusive chiral superconductivity.
Quantum View of a Superconductor-Semiconductor Junction
Currently, electronic device technology is based mainly on semiconductors. It first emerged in the middle of the 20:th: century and has improved ever since. Further technological advances including energy efficiency and information security might profit from exploiting quantum mechanical properties that are present in superconductors. The challenge is how to combine the two states and to make sure to get the best of both electrical worlds. A collaboration of researchers from Cornell and the Paul Scherrer Institute (PSI) in Switzerland grew thin films of the superconductor niobium nitride (NbN) on top of gallium nitride (GaN), a semiconductor and vital component in many optical and power electronics. The team measured the electronic properties of the two materials directly at their interface using soft-X-ray angle-resolved photoelectron spectroscopy (ARPES).
Discovery of Multimagnon Bound States in FeI2
Magnons, or spin waves, are quasiparticles describing collective spin excitations of ordered magnets. When magnon-magnon interactions are strong, new multi-magnon excitations and bound states can emerge. Here, magnetic THz spectroscopy of the layered magnet FeI2 revealed a complex series of excitations beyond the one-magnon picture.
Metal Selenide-Carbon Nanofiber Composites for Battery Anodes
The ever-growing demand for electric vehicles and portable electronic devices continues to drive the craving for lightweight, high-energy-density, and long-lifespan batteries. Currently used lithium-ion batteries are limited by the capacity of the electrode and the scarcity of resources (lithium). The search for next-generation materials not only seeks to replace lithium with sodium but to provide suitable anode materials. Metal selenides (:M:Se, :M := Sn, Fe, Ni, Cu) offer the desired conductivity, stability, cost-effectiveness, and higher theoretical capacity compared to commercial graphite.
PARADIM – an Incubator for Collaborations II
Since the discovery of high-temperature superconductivity in copper-based oxides (cuprates), there has been a sustained effort to understand its origin and to discover new superconductors based on similar building principles. Indeed, superconductivity has recently been discovered in the doped rare-earth nickelate Nd:0.8:Sr:0.2:NiO:2:. Undoped NdNiO:2: is the infinite-layer end member of a larger family of layered nickelates, which can be explored by molecular-beam epitaxy (MBE).
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