Highlights
Expanding the Capabilities of Lab-Based ARPES on Quantum Materials
Here, PARADIM’s In-House Team developed a simple algorithmic method to separate the two components from ARPES spectra collected with doublet emission sources.
Topological Surface States in a Kondo Insulator
Topological Kondo Insulators offer a unique route to topological surface states with great potentials both for devices as well as to probe the fundamental physics of topology. The NHMFL team came to PARADIM to gain access to what is only the second known topological Kondo insulator, YbB12. Working with PARADIM trainee Lucas Pressley and PARADIM REU Julia Trowbridge, laser floating zone was successfully used to produce untwinned single crystals of YbB12, a very high, incongruently melting, boride, marking the first time this material was produced outside of Japan, and the first time with the laser FZ technique.
Suboxide Molecular-Beam Epitaxy—Translating a new Concept into β-Ga2O3 Transistors
In 2020 PARADIM’s in-house team—working with collaborators at Penn State—developed (and patented) a new variant of molecular-beam epitaxy (MBE) called “suboxide MBE.” In contrast to conventional MBE where the molecular beams are elemental, in suboxide MBE the molecular beams are pre-oxidized. This method has since been widely applied by PARADIM users in 20 publications utilizing suboxide MBE + over 20 active user projects).
Strain or Defects? An important question for the nickelate superconductors answered via a Platform—A User Facility that Facilitates Collaboration
We demonstrate a method to synthesize superconducting layered square-planar nickelate thin films and set limits on the ability to strain these compounds via epitaxy.
Gate-tunable heavy fermions in a moiré Kondo lattice
Here, members of PARADIM’s In-House Research Team demonstrate a model system created by stacking a pair of monolayer semiconductors, providing a simpler way to study confounding quantum behavior, from heavy fermions to exotic quantum phase transitions.
The Multiplicative Effect of Knowledge Sharing
This publication marks the first time that KTaO3 films have been grown by MBE. The approach used overcame the technical challenges of (1) the low vapor pressure of tantalum (normally impossible in a stable MBE effusion cell due to the low vapor pressure of tantalum) and (2) the safety issues of safely handling potassium, which is highly flammable. The resulting films have the highest structural quality of any KTaO3 films ever grown judging from the narrowness of the x-ray diffraction rocking curves and rather featureless microstructure revealed by STEM.
PARADIM – an Incubator for Collaborations III
A team of experimentalists and theorists connecting at PARADIM have discovered a new antiferromagnetic metal. Their discovery adds to the rich variety of physical properties exhibited by rare-earth nickelates: superconductivity (previously discovered by the core members of this team), metal-insulator transitions, and antiferromagnetic insulators. This latest discovery provides additional insights into the coupling of spin, charge, and lattice degrees of freedom when these elements are combined.
Modulating Catalytic Activity using a Ferroelectric
An emerging opportunity for ferroelectrics is to modulate catalytic activity. Such behavior has been reported in a prior PARADIM publication by this same user utilizing MBE-grown epitaxial BaTiO3 thin films with atomically sharp interfaces as model surfaces to demonstrate the effect of ferroelectric polarization on the electronic structure, intermediate binding energy, and electrochemical activity toward the hydrogen evolution reaction (HER).
X-ray micro-computed tomography informs materials discovery
Here, members of PARADIM’s in-house research team collaborated with external users and summer school participants on case studies of µCT informing materials design of electronic and quantum materials, benefitting the characterization of inclusions, twinning, and low-angle grain boundaries and optimizing crystal growth processes. The work discusses recent improvements in µCT instrumentation that enable elemental analysis and orientation to be obtained on crystalline samples.
Electrical Control of Inversion Symmetry
Symmetry in crystalline materials largely dictates their properties and new functionalities can arise when inversion symmetry is broken and disappear when it is restored. PARADIM users have made a new material in which by applying a voltage they can "turn off" and "turn on" the inversion symmetry of the atomic arrangement. Inversion symmetry is what happens when you turn an object inside out.
The Electronic Phase Diagram of Moiré Superlattices
Members of PARADIM’s in-house research team have used Monte Carlo simulations to study intermediate phases occurring at fractional electron counts between the charge-ordered states in the strong coupling limit. The team found two distinct stripe solid states to be each preceded by distinct types of nematic states and describes a microscopic mechanism that stabilizes each of the nematic states.
From Machine Learning to Discovery of New Family Member
Thin films of Ba3In2O6 had never been made and PARADIM researchers were able to grow the desired phase using a new variant of molecular-beam epitaxy (MBE), suboxide MBE, developed in PARADIM. In addition to succeeding in the growth of the targeted phase, Ba3In2O6, PARADIM researchers also discovered a new barium indate phase with an even simpler crystal structure, Ba4In2O7, that is analogous to the first high-temperature cuprate superconductor discovered, (La,Ba)2CuO4.
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