Highlights
Stromataxy – Enabling the (otherwise) Unreachable
The properties of any material are largely governed by its constituting elements and the arrangement of those atoms. Different structures can result in vastly different behavior, even for the same chemical composition. Thus, to achieve a desired structure—the one with the desired properties—it is vital to be able to navigate synthesis pathways.:Here, users from the Naval Research Lab wanted to grow ScFeO3, where five different ways are known in which the same atoms can be arranged. In the past, different substrates have been used to select between the various polymorphs by altering the energetics of materials growth through a process known as epitaxial stabilization.
Cleaning up a Quantum Material: from Quantum Enigma to Quantum Oscillations
Sr:2:RuO:4: is the most disorder-sensitive superconductor known. It has also been a leading candidate for a novel type of quantum computer that would enable calculations to occur over much longer time scales before suffering decoherence than is the case for today’s superconductor-based quantum computers. Establishing whether Sr:2:RuO:4: is viable for such applications would be aided by the ability to make structures containing superconducting Sr:2:RuO:4: films.
Quantification of Interfacial Electron-Phonon Coupling from Photoemission Replica Bands in a High-Tc Superconductor
The observation of replica bands by angle-resolved photoemission spectroscopy enables the study of electron-phonon coupling at low carrier densities, particularly in monolayer FeSe/SrTiO3. Theoretical work suggests that the electrons in the ultra-thin FeSe layer couple to optical phonons in the SrTiO3 substrate that thereby contributes to the enhanced superconducting pairing temperature. So far, the inherent fragility of such single-layer thick materials and the weak intensity of replica features has limited the quantitative evaluation of their nature.
PARADIM – an Incubator for Collaborations
Important applications like ultrashort pulsed lasers, sensors, laser amplifiers, and digital optical information processing, depend on materials with nonlinear optical properties—that is the material’s nonlinear interaction with electromagnetic waves, :e.g.:, light.
Cryo-STEM Unveils Electronic Order at the Atomic Scale
In quantum materials, electrons can interact strongly with each other and with the atomic lattice, giving rise to novel electronic states with functionalities not achievable in conventional materials. At the atomic scale, the local crystal symmetries are governed by variations in the charge distribution and subtle atomic displacements, dramatically affecting the material’s properties.
Discovery of “Pseudogap” Behavior in a Monolayer Thick High-Temperature Superconductor
Members of PARADIM’s in-house research team have employed a combination of angle-resolved photoemission spectroscopy and in situ resistivity measurements to simultaneously probe both the electronic states and superconducting behavior of pristine monolayer FeSe/SrTiO3.
Discovery of “Pseudogap” Behavior in a Monolayer Thick High-Temperature Superconductor
The ability to produce pristine atomic interfaces by growing the structures atom-by-atom :via: molecular beam epitaxy has opened the door to an entirely new class of emergent phenomena in the form of interface quantum materials. One remarkable example of such a material system is the interface between monolayer iron selenide (FeSe) films and SrTiO:3:, where superconductivity can be observed at dramatically higher temperatures compared to 8 K of bulk FeSe. So far, the inherent fragility of such ultra-thin layers has prevented the direct study of superconductivity :via: direct probes like electrical resistivity.
Remote Epitaxy of 3D functional semiconductors and oxides using Graphene as the Interface layer
H. Paik:, :S. Xie:, H. Shin, C. Choi, J.H. Le, :C. Dong:, :J.A. Robinson (2DCC):, :J.-H. Lee:, J.-H. Ahn, G.Y. Yeom, :D.G. Schlom (PARADIM):, J. Kim (MIT):Project Summary::Remote epitaxy has drawn attention as it offers epitaxy of functional materials that can be released from the substrates with atomic precision, thus enabling production and heterointegration of flexible, transferrable, and stackable freestanding single-crystalline membranes. In this highlight, 2DCC and PARADIM team up to work with the inventor of remote epitaxy, Prof. Kim (MIT), to unveil the respective roles and impacts of the substrate material, graphene, substrate–graphene interface, and epitaxial material for electrostatic coupling of these materials, which governs cohesive ordering and can lead to single-crystal epitaxy in the overlying film.
The Highest Resolution Microscope, enabled by a new detector technology, reaches an ultimate resolution limit – the vibrations of atoms themselves
Electron microscopy is a widespread and often essential tool for structural and chemical analysis at the atomic level. Image resolution is dominated by the energy (or wavelength) of the electron beam and the quality of the lens. By combining our new design of electron microscope pixel array detector (EMPAD), which has the dynamic range to record the complete distribution of transmitted electrons at every beam position and a phase retrieval algorithm to process the data, PARADIM’s in-house research team has increased the spatial resolution well beyond the traditional lens limitations, setting a world record in 2018 for the highest resolution microscope (0.39 Å Abbe resolution [1]) at the same dose and imaging conditions where conventional imaging modes reach only 0.98 Å. The EMPAD is the culmination of over a decade of detector development at Cornell, supported by NSF (through CHESS, CCMR), DOE, the WM Keck Foundation, and the Kavli Institute, and has been commercially licensed by ThermoFisher Scientific and is now manufactured and sold at scale.
The Highest Resolution Microscope, enabled by a new detector technology, reaches an ultimate resolution limit – the vibrations of atoms themselves
By combining PARADIM’s new design of electron microscope pixel array detector (EMPAD), which has the dynamic range to record the complete distribution of transmitted electrons at every beam position and a phase retrieval algorithm to process the data, the research team has increased the spatial resolution well beyond the traditional lens limitations, setting a world record in 2018 for the highest resolution microscope.
Beyond Terfenol-D
For nearly 50 years, Terfenol-D (Tb:x:Dy:1-:x:Fe:2:) has reigned as the material for which an applied magnetic field results in the greatest change in shape, a property known as magnetostriction. A distant second to Terfenol-D is Galfenol (Fe:1–:x:Ga:x:), the best magnetostrictor free of rare-earth elements.
Unit-Cell-Thick Domains in Quasi-2D Ferroelectric Material
Many electronic devices, like non-volatile high-density memories, ultra-fast switches, and thin film capacitors, rely on ferroelectric materials—a class of materials with spontaneous electrical polarization which can be reproducibly switched. In two-dimensional (2D) and quasi-2D ferroelectric materials the size of ferroelectric domains can be small which may enable the miniaturization of devices. Understanding of ferroelectric domain structure at the atomic scale is, however, limited, hindering the development of functional device units at the microscopic level.
Showing 37 to 48 of 75