Publications
Using the Ecology and Evolution-Measuring Achievement and Progression in Science assessment to measure student thinking across the Four-Dimensional Ecology Education framework
The newly developed Four-Dimensional Ecology Education (4DEE) framework, produced by the Ecological Society of America, provides updated guidance for undergraduate instruction. To help instructors align their courses to this framework and assess student progress toward its goals, we have recoded the comprehensive programmatic assessment Ecology and Evolution-Measuring Achievement and Progression in Science (EcoEvo-MAPS) and reanalyzed a national dataset of over 2000 undergraduate student responses.
Optical signatures of the chiral anomaly in mirror-symmetric Weyl semimetals
The chiral anomaly is a characteristic phenomenon of Weyl fermions, which has condensed matter realizations in Weyl semimetals. Efforts to observe smoking gun signatures of the chiral anomaly in Weyl semimetals have mostly focused on a negative longitudinal magnetoresistance in electronic transport. Unfortunately, disentangling the chiral anomaly contribution in transport or optical measurements has proven nontrivial. Recent works have proposed an alternative approach of probing pseudoscalar phonon dynamics for signatures of the chiral anomaly in non-mirror-symmetric crystals.
Density matrix renormalization group study of superconductivity in the triangular lattice Hubbard model
With the discovery of strong-coupling physics and superconductivity in moiré superlattices, it is essential to have an understanding of strong-coupling driven superconductivity in systems with trigonal symmetry. The simplest lattice model with trigonal symmetry is the triangular lattice Hubbard model. Although the triangular lattice spin model is a heavily studied model in the context of frustration, studies of the hole-doped triangular lattice Hubbard model are rare.
Anisotropic spin-orbit torque generation in epitaxial SrIrO3 by symmetry design
Spin-orbit coupling (SOC), the interaction between the electron spin and the orbital angular momentum, can unlock rich phenomena at interfaces, in particular interconverting spin and charge currents. Conventional heavy metals have been extensively explored due to their strong SOC of conduction electrons. However, spin-orbit effects in classes of materials such as epitaxial 5d-electron transition-metal complex oxides, which also host strong SOC, remain largely unreported.
Lattice construction of duality with non-Abelian gauge fields in 2+1D
The lattice construction of Euclidean path integrals has been a successful approach of deriving 2+1D field theory dualities with a U(1) gauge field. In this work, we generalize this lattice construction to dualities with non-Abelian gauge fields. We construct the Euclidean space-time lattice path integral for a theory with strongly interacting SO(3) vector bosons and Majorana fermions coupled to an SO(3) gauge field and derive an exact duality between this theory and the theory of a free Majorana fermion on the space-time lattice.
Effective Spin-Mixing Conductance of Heavy-Metal–Ferromagnet Interfaces
The effective spin-mixing conductance (Geff↑↓) of a heavy-metal-ferromagnet (HM-FM) interface characterizes the efficiency of the interfacial spin transport. Accurately determining Geff↑↓ is critical to the quantitative understanding of measurements of direct and inverse spin Hall effects. Geff↑↓ is typically ascertained from the inverse dependence of magnetic damping on the FM thickness under the assumption that spin pumping is the dominant mechanism affecting this dependence.
Lattice models for non-Fermi liquids with tunable transport scalings
A variety of exotic non-Fermi liquid (NFL) states have been observed in many condensed matter systems, with different scaling relations between transport coefficients and temperature. The "standard" approach to studying these NFLs is by coupling a Fermi liquid to quantum critical fluctuations, which potentially can drive the system into a NFL. In this work we seek for an alternative understanding of these various NFLs in a unified framework.
Selection of CVD diamond crystals for x-ray monochromator applications using x-ray diffraction imaging
A set of 20 single crystal diamond plates synthesized using chemical vapor deposition (CVD) was studied using X-ray diffraction imaging to determine their applicability as side-bounce (single-reflection) Laue monochromators for synchrotron radiation. The crystal plates were of optical grade (as provided by the supplier) with (001) nominal surface orientation. High dislocation density was found for all samples. Distortions in the crystal lattice were quantified for low-index Laue reflections of interests using rocking curve topography.
Understanding the Stiff-to-Compliant Transition of the Meniscal Attachments by Spatial Correlation of Composition, Structure, and Mechanics
Recently, the scientific community has shown considerable interest in engineering tissues with organized compositional and structural gradients to mimic hard-to-soft tissue interfaces. This effort is hindered by an incomplete understanding of the construction of native tissue interfaces. In this work, we combined Raman microscopy and confocal elastography to map compositional, structural, and mechanical features across the stiff-to-compliant interface of the attachments of the meniscus in the knee.
Fermi surface reconstruction by a charge density wave with finite correlation length
Even a small amplitude charge-density wave (CDW) can reconstruct a Fermi surface, giving rise to new quantum oscillation frequencies. Here, we investigate quantum oscillations when the CDW has a finite correlation length ζ - a case relevant to the hole-doped cuprates. By considering the Berry phase induced by a spatially varying CDW phase, we derive an effective Dingle factor that depends exponentially on the ratio of the cyclotron orbit radius, Rc, to ζ.