Publications
Large spin–orbit torque in bismuthate-based heterostructures
The wider application of spintronic devices requires the development of new material platforms that can efficiently be used to manipulate spin. Bismuthate-based superconductors are centrosymmetric systems that are generally thought to offer weak spin–orbit coupling. Here we report a large spin–orbit torque driven by spin polarization generated in heterostructures based on the bismuthate BaPb1−xBixO3 (which is in a non-superconducting state). Using spin-torque ferromagnetic resonance and d.c.
High-throughput ab initio design of atomic interfaces using InterMatch
Forming a hetero-interface is a materials-design strategy that can access an astronomically large phase space. However, the immense phase space necessitates a high-throughput approach for an optimal interface design. Here we introduce a high-throughput computational framework, InterMatch, for efficiently predicting charge transfer, strain, and superlattice structure of an interface by leveraging the databases of individual bulk materials.
Realizing a tunable honeycomb lattice in ABBA-stacked twisted double bilayer WSe2
The ideal honeycomb lattice, featuring sublattice and SU(2) spin rotation symmetries, is a fundamental model for investigating quantum matters with topology and correlations. With the rise of the moiré-based design of model systems, realizing a tunable and symmetric honeycomb lattice system with a narrow bandwidth can open access to new phases and insights. We propose the ABBA-stacked twisted double bilayer WSe2 as a realistic and tunable platform for reaching this goal.
Realizing a tunable honeycomb lattice in ABBA-stacked twisted double bilayer WSe2
The ideal honeycomb lattice, featuring sublattice and SU(2) spin rotation symmetries, is a fundamental model for investigating quantum matter with topology and correlations. With the rise of the moiré-based design of model systems, realizing a tunable and symmetric honeycomb lattice system with a narrow bandwidth can open access to new phases and insights. We propose the ABBA-stacked twisted double bilayer WSe2 as a realistic and tunable platform for reaching this goal. Adjusting the twist angle allows the bandwidth and the ratio between hopping parameters of different ranges to be tuned.
Considerations about future hard x-ray area detectors
X-ray sources continue to advance in both intensity and temporal domains, thereby opening new ways to analyze the structure and properties of matter, provided that the resultant x-ray images can be efficiently and quantitatively recorded. In this perspective we focus on specific limitations of pixel area x-ray detectors. Although pixel area x-ray detectors have also advanced in recent years, many experiments are still detector limited.
Polycrystallinity Enhances Stress Buildup around Ice
Damage caused by freezing wet, porous materials is a widespread problem but is hard to predict or control. Here, we show that polycrystallinity significantly speeds up the stress buildup process that underpins this damage. Unfrozen water in grain-boundary grooves feeds ice growth at temperatures below the freezing temperature, leading to fast stress buildup. These stresses can build up to levels that can easily break many brittle materials.
Context affects student thinking about sources of uncertainty in classical and quantum mechanics
Measurement uncertainty is an important topic in the undergraduate laboratory curriculum. Previous research on student thinking about experimental measurement uncertainty has focused primarily on introductory-level students' procedural reasoning about data collection and interpretation. In this paper, we extended this prior work to study upper-level students' thinking about sources of measurement uncertainty across experimental contexts, with a particular focus on classical and quantum mechanics contexts.
Unveiling the double-peak structure of quantum oscillations in the specific heat
Quantum oscillation phenomenon is an essential tool to understand the electronic structure of quantum matter. Here we report a systematic study of quantum oscillations in the electronic specific heat C el in natural graphite. We show that the crossing of a single spin Landau level and the Fermi energy give rise to a double-peak structure, in striking contrast to the single peak expected from Lifshitz-Kosevich theory. Intriguingly, the double-peak structure is predicted by the kernel term for C el/T in the free electron theory.
BLAST: A Wafer-Scale Transfer Process for Heterogeneous Integration of Optics and Electronics
A general transfer method is presented for the heterogeneous integration of different photonic and electronic materials systems and devices into a single substrate. Called BLAST, for Bond, Lift, Align, and Slide Transfer, the process works at wafer scale and offers precision alignment, high yield, varying topographies, and suitability for subsequent lithographic processing. BLAST's capabilities is demonstrated by integrating both GaAs and GaN µLEDs with silicon photovoltaics to fabricate optical wireless integrated circuits that up-convert photons from the red to the blue.
Disorder Operator and Renyi Entanglement Entropy of Symmetric Mass Generation
In recent years a consensus has gradually been reached that the previously proposed deconfined quantum critical point (DQCP) for spin-1/2 systems, an archetypal example of quantum phase transition beyond the classic Landau's paradigm, actually does not correspond to a true unitary conformal field theory (CFT). In this work we carefully investigate another type of quantum phase transition supposedly beyond the similar classic paradigm, the so called ``symmetric mass generation" (SMG) transition proposed in recent years.