Publications

Showing 27 results for Author: Zachary J. Morgan

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  • Sep, 2026

    Journal

    Contrasting structural reversibility and magnetic correlations in isostructural honeycomb magnets CrCl3 and 𝛼−RuCl3

    We report a comparative neutron single crystal diffraction study of the structural and magnetic properties of layered halides CrCl3 and 𝛼−RuCl3. They host a honeycomb arrangement of transition metal ions with distinct electronic configurations and undergo a first-order structural transition between high-temperature 𝐶⁢2/𝑚 and low-temperature 𝑅⁢‾‾‾3. Both compounds show a st…

  • Aug, 2026

    Journal

    Coexisting paramagnetic spins and long-range magnetic order in Ba4⁢(Ru0.92⁢Ir0.08)3⁢O10

    We investigate the effect of dilute Ir substitution on the magnetism of the trimer-based ruthenate Ba4⁢Ru3⁢O10 using neutron diffraction, magnetic susceptibility measurements, first-principles calculations, and atomistic simulations. Neutron diffraction shows that Ir doping preserves the zigzag antiferromagnetic structure and the ordered-moment magnitude of the parent comp…

  • Aug, 2026

    Journal

    Temporal and spatial separations between spin glass and short-range order

    Broken-symmetry-induced order parameters account for many phenomena in physics. For spin glasses, this framework dictates the theoretical construction, whereas experiments have only established dynamical behaviors but not the physical entity. Experimental techniques have limitations when the spin glass is probed as an isolated state. Here, we create an evolution from a lon…

  • Aug, 2026

    Journal

    Uniaxial Strain Tuned Magnetism of the Altermagnet Candidate H-FeS

    Altermagnets are a newly recognized class of magnetic materials characterized by compensated spin configurations while still breaking time-reversal symmetry and exhibiting unconventional transport phenomena. Hexagonal FeS (h-FeS) is a recently identified altermagnet candidate that shows a spontaneous anomalous Hall effect (AHE) accompanied by a tiny net magnetization. Here…

  • Aug, 2026

    Journal

    Correlation between complex spin textures and the magnetocaloric and Hall effects in Eu⁢(Ga1−𝑥⁢Al𝑥)4 (𝑥=0.9, 1)

    Determining the electronic phase diagram of a quantum material as a function of temperature (𝑇) and applied magnetic field (𝐻) forms the basis for understanding the microscopic origin of transport properties, such as the anomalous Hall effect (AHE) and topological Hall effect (THE). For many magnetic quantum materials, including Eu⁢Al4, a THE arises from a topologically pr…

  • Jul, 2026

    Journal

    Magnetism and magnetoelastic effect in the two-dimensional van der Waals multiferroic CuCrP2S6

    We report a magnetic and neutron diffraction study on the ground state magnetism and field evolution of single-crystal van der Waals multiferroic CuCrP2⁢S6. The ordered moments align along the 𝑏 axis in the “𝐴-type” antiferromagnetic configuration with a spin-flop transition along the same direction. Field application along 𝑎 introduces a smooth transition to a fully polar…

  • Mar, 2026

    Journal

    On the ordering mechanism of Cu+ in 2D van der Waals multiferroic CuCrP2S6

    CuCrP2S6 is a van der Waals multiferroic where the tunable Cu+ sublattice underpins its exceptional ferroelectric and electronic switching properties. Yet, the microscopic mechanism governing Cu+ ordering has remained elusive. Here, we combine single-crystal X-ray and neutron diffraction with pair distribution function analysis to uncover a temperature-driven evolution of…

  • Mar, 2026

    Conference Paper

    Integrating ORNL’s HPC and Neutron Facilities with a Performance-Portable CPU/GPU Ecosystem

    We explore the development of a performance-portable CPU/GPU ecosystem to integrate two of the US Department of Energy’s (DOE’s) largest scientific instruments, the Oak Ridge Leadership Computing facility and the Spallation Neutron Source (SNS), both of which are housed at Oak Ridge National Laboratory. We select a relevant data reduction workflow use-case to obtain the di…

  • Dec, 2025

    Journal

    Hydrogen density mapping in biomolecular crystals through dynamic nuclear polarization

    Many fundamental biological processes, including those in photosynthetic reaction centers and enzyme active sites, involve charge and energy transfer, bond cleavage, protonation and hydrogen bonding. Because H atoms play such central roles in these reactions, accurately determining their positions is essential. Yet, conventional X-ray crystallography primarily resolves the…

  • Nov, 2025

    Journal

    Structurally Frustrated Remeika Phases: Tolerance Factor and Non-Kramers’ Ion Effects

    Quantum materials that are found on the verge of structural, magnetic, and electronic instabilities are deep reservoirs for exotic phenomena. Our criteria to study the reported Ln5Ru6Sn18 (Ln = Gd, Tb) are guided by the tolerance factor for Remeika phases─a class of intermetallic compounds with the general formula A3M4X13 (where A = rare-earth element, M = transition metal…

  • Oct, 2025

    Journal

    Persistent short-range spin fluctuation in rare-earth substituted square lattice Sr2⁢Ir0.89⁢Tb0.11⁢O4

    Sr2⁢IrO4, a prototypical 𝐽eff=1/2 square lattice system, is widely studied for novel physics. While transition metal substitution effects are well explored, rare-earth doping at the Ir4+ site is less explored. Here we present a detailed magnetization and neutron diffraction study on Sr2⁢Ir1−𝑥⁢Tb𝑥⁢O4 (𝑥=0.11). The system tends to adopt an in-plane antiferromagnetic configur…

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