Hi, I'm George Yumnam

Postdoctoral Fellow

Stewart Blusson Quantum Matter Institute

Department of Physics and Astronomy

The University of British Columbia

About Me

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.

Education Background

Research Areas

Quantum and Unconventional Magnetism
Neutron & X-ray Scattering
Experimental Condensed Matter
Quantum Materials
Density Functional Theory

Current Research Initiatives

Magnon-Phonon Interactions

Magnon-Phonon Interactions

In this line of work, 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. The broader goal is to understand when magnon-phonon coupling can be engineered to either enhance or suppress heat and spin currents in candidate magnonic and thermoelectric devices.

Neutron Scattering Magnons Thermal Transport
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High-Entropy Oxides

High-Entropy Oxides

Here we study chemically complex, high-entropy oxides and characterize them mainly using neutron and X-ray diffraction and total scattering to map how multi-cation disorder and strain fields shape their magnetic landscape. By focusing on how scattering signatures evolve with temperature and field, and comparing to reported macroscopic responses, we distinguish conventional glassy freezing from genuinely frustrated collective states. Statistical and mean-field models then link the enormous cation-configuration space to experimentally observed scattering signatures, with an eye toward designing disordered oxides that host robust, tunable magnetic functionalities.

Disorder Magnetism X-ray Scattering
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Honeycomb Lattice Magnetism

Honeycomb Lattice Magnetism

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. Simple models then connect local vertex configurations and magnetic-charge textures to non-reciprocal transport signatures and ultra-low forward-voltage behaviour, highlighting routes toward neuromorphic elements and energy-efficient magnetic diodes built from geometrically engineered frustration.

Frustrated Systems Topology Magnetism
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Quantum Magnetism

Quantum Magnetism

In this initiative, 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 that go beyond simple magnon pictures. The aim is to identify chemically accessible platforms where entangled ground states and robust collective modes coexist, providing realistic opportunities to couple quantum spin degrees of freedom to spintronic or quantum-information architectures.

Quantum Materials Spintronics DFT
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Selected Publications

Constraints on magnetism and correlations in RuO₂ from lattice dynamics and Mössbauer spectroscopy

George Yumnam, Parul R. Raghuvanshi, John D. Budai, Dipanshu Bansal, Lars Bocklage, et al.

Cell Reports Physical Sciences, 2025

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Magnon gap tuning in lithium-doped MnTe

George Yumnam, Duncan H. Moseley, Joseph A. M. Paddison, Christiana Z. Suggs, Emma Zappala, et al.

Physical Review B, 109, 214434 (2024)

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Field and temperature tuning of magnetic diode in permalloy honeycomb lattice

George Yumnam, Moudip Nandi, Pousali Ghosh, Amjed Abdullah, Mahmoud Almasri, et al.

Materials Today Advances, 18, 100386 (2023)

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Magnetic charge and geometry confluence for ultra-low forward voltage diode in artificial honeycomb lattice

George Yumnam, Jiasen Guo, Yiyao Chen, Ashutosh Dahal, Pousali Ghosh, et al.

Materials Today Physics, 22, 100574 (2022)

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Teaching & Mentoring

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.

Collaboration Opportunities

Co-advised Students

Joint projects on neutron and X-ray scattering studies of magnon dynamics and related quantum materials.

Visiting Researchers

Short-term visits to pair scattering experiments with shared analysis notebooks and open data pipelines.

Collaborative Proposals

Partners on neutron/X-ray scattering experiments on magnetic and quantum materials with shared authorship plans.

Let's Work Together

I'm always interested in hearing about new projects and opportunities.