George Yumnam
Postdoctoral Fellow
Stewart Blusson Quantum Matter Institute
Department of Physics and Astronomy
The University of British Columbia
Postdoctoral Fellow
Stewart Blusson Quantum Matter Institute
Department of Physics and Astronomy
The University of British Columbia
I am a postdoctoral fellow at the Stewart Blusson Quantum Matter Institute (SBQMI) at the University of British Columbia and an experimental condensed-matter physicist specializing in neutron and X-ray scattering. My research focuses on how spin, lattice, and crystal-field degrees of freedom hybridize and evolve under disorder, field, pressure, and chemical tuning—shaping magnetic excitations and emergent functionality in quantum materials.
My research is motivated by a central question in quantum materials: how collective excitations emerge, persist, and hybridize in ordered magnets and unconventional magnets far from ideal order. I focus on understanding how spin dynamics couple to lattice, crystal-field, and electronic degrees of freedom in the presence of disorder, dilution, and external tuning parameters, and how these interactions reshape magnetic spectra across energy and temperature scales.
By developing quantitatively constrained, experimentally grounded descriptions of these coupled excitations, my work aims to uncover organizing principles that govern robustness, breakdown, and reconfiguration of magnetic behavior in complex quantum magnets—providing a foundation for rational control of spin-based phenomena in real materials.
At the neutron scattering beamline
We use inelastic neutron and resonant X-ray scattering on itinerant antiferromagnets and correlated insulators to resolve how magnon branches hybridize with optical phonons. By quantifying dispersion renormalization, linewidth broadening, and spectral-weight transfer, we build microscopic models that connect spin-lattice coupling to macroscopic transport properties.
We characterize chemically complex, high-entropy oxides using neutron and X-ray diffraction and total scattering to map how multi-cation disorder and strain fields shape their magnetic landscape. Statistical and mean-field models link the enormous cation-configuration space to experimentally observed scattering signatures.
We work on artificial permalloy honeycomb lattices that realize tunable, frustrated Ising-like networks. We track how field history, temperature, and geometry drive the system between ice-like, charge-ordered, and diode-like conducting states, and relate these regimes to changes in their collective magnetic configurations.
I work on model quantum magnets where reduced dimensionality, frustration, and anisotropic exchange produce large quantum fluctuations. Using elastic and inelastic neutron scattering together with numerical modelling, we search for proximate spin-liquid regimes, multipolar orders, and excitation continua beyond simple magnon pictures.
Cell Reports Physical Sciences, 2025
View Publication →Physical Review B, 112, 014450 (2025)
View Publication →Advanced Science, 8, 2004103 (2021)
View Publication →Materials Today Physics, 22, 100574 (2022)
View Publication →iScience, 24, 102206 (2021)
View Publication →Chemistry of Materials, 31, 5145-5151 (2019)
View Publication →As a postdoctoral researcher, I typically join projects once a concrete materials or scattering question is on the table. I am not currently hiring students directly, but I am very happy to co-advise, mentor on neutron and X-ray scattering experiments, and collaborate on joint proposals. I follow a bottom-up approach in teaching physics at the college and graduate level.
Joint projects on neutron and X-ray scattering studies of magnon dynamics and related quantum materials.
Short-term visits to pair scattering experiments with shared analysis notebooks and open data pipelines.
Partners on neutron/X-ray scattering experiments on magnetic and quantum materials with shared authorship plans.
I'm always open to collaboration, mentorship, and new research conversations.