Showing 31 results for Author: Fankang Li
Jul, 2026
Journal
The Laue neutron macromolecular crystallography beamline IMAGINE at the High Flux Isotope Reactor (HFIR) is undergoing a major upgrade to incorporate the Dynamic Nuclear Polarization (DNP) technique. Upon completion, the new IMGAINE-X instrument is expected to enhance the signal-to-noise ratio of the diffraction data by an order of magnitude. To take full advantage of the…
Dec, 2025
Journal
Bismuth exhibits a Peierls distortion away from a simple cubic structure, reflecting both an anharmonic potential energy surface and electron-phonon coupling in a semimetal. It has attracted considerable interest in studies of low-temperature thermal transport, thermoelectrics, and optical excitation of coherent phonon. Yet, the temperature-dependence of phonons in bismuth…
Nov, 2025
Journal
Unveiling the interplay between spin density wave (SDW) and charge density wave (CDW) orders in correlated electron materials is important in obtaining a comprehensive understanding of their electronic, structural, and magnetic properties. Kagome lattice materials are interesting because their flat electronic bands, Dirac points, and Van Hove singularities can enable a var…
Aug, 2025
Journal
Neutron spin-phase imaging (NSPI) capability was developed to study the magnetization distribution of an amorphous magnetic thin film. The local magnetization under different applied magnetic fields between 0.09 and 1.36 mT was investigated. The developed radio frequency flippers showed more than 95% flipping efficiency under these fields. A spatial resolution of ~0.4 mm a…
Jul, 2025
Journal
Larmor diffraction (LD) is a neutron scattering technique that offers enhanced resolution by harnessing the Larmor precession of neutron spins in a magnetic field. By encoding subtle changes in neutron momentum transfer into significant alterations in the Larmor phase of neutron spins, LD can be employed to measure lattice expansion, lattice distortion, and mosaicity with…
Jul, 2025
Journal
A superconducting electromagnetic nutator (EMN) capable of generating a magnetic field vector along an arbitrary direction on a 2D plane has been designed. Its performance in precisely manipulating the neutron polarization vector has been tested at the HB2-D polarized development beamline at the High Flux Isotope Reactor. Unlike mechanical nutators that require physical ha…
Jun, 2025
Journal
Neutron resonance spin echo (NRSE) technique has the potential to increase the Fourier time and energy resolution in neutron scattering by using radio frequency (rf) neutron spin-flippers. However, aberrations arising from variations in the neutron path length between the rf flippers reduce the polarization. Here, we develop and test a transverse static-field magnet, a ser…
May, 2025
Journal
Spin-echo small-angle neutron scattering (SESANS) allows structural measurements from 10s of nanometers out to 10s of micrometers, significantly broader than conventional small-angle neutron scattering (SANS). This is achieved by encoding the scattering angle into the Larmor phase of neutron spin. Multiple SESANS instruments have been developed, each employing distinct met…
Feb, 2025
Journal
We present a resonant-mode, transverse-field, radio-frequency (rf) neutron spin flipper design that uses high-temperature superconducting films to ensure sharp transitions between uniform magnetic field regions. Resonant mode allows for low-power, high-frequency operation but requires strict homogeneity of the magnetic fields inside the device. This design was found to eff…
Nov, 2024
Journal
The continued advancement of complex materials often requires a deeper understanding of the structure–function relationship across many length scales, which quickly becomes an arduous task when multiple measurements are required to characterize hierarchical and inherently heterogeneous materials. Therefore, there are benefits in the simultaneous characterization of multipl…
Sep, 2024
Journal
Intraparticle entanglement of individual particles such as neutrons could enable another class of scattering probes that are sensitive to entanglement in quantum systems and materials. In this work, we present experimental results demonstrating quantum contextuality as a result of entanglement between the spin and energy modes (i.e., degrees of freedom) of single neutrons…
Jul, 2024
Journal
We show the implementation of superconducting magnetic Wollaston prisms for spin echo small-angle neutron scattering. Two calibration methods for the spin echo length are presented: one utilizing spin echo modulated small-angle neutron scattering and the other based on the neutron refraction by quartz wedge crystals. Our experimental results with polystyrene nano-particle…