Bio

Hello!
In my physics PhD at Stanford, I grew crystals of Zn-Barlowite. These crystals are strong candidates to be a new state of magnetic matter called a “quantum spin liquid”. Much of my thesis work was dedicated to proving that these materials have novel quantum magnetic properties through neutron scattering. This work resulted in a nature physics paper that is currently generating a lot of buzz within my subfield of condensed matter physics (https://arxiv.org/html/2504.06491v1).

This novel state of matter is interesting to us because it is a strong candidate to store memory in future large-scale quantum computers. I did some calculations, and I think that it takes roughly 10^19 bits of information to faithfully represent the intricate internal quantum magnetic state. For comparison, the human brain encodes about 10^16 bits of information.
What’s most fascinating to me about these quantum spin liquid crystals is that they also grow in nature. I will emphasize that this is absolutely anomalous for a material with such unique quantum properties. The vast majority of materials grown by my colleagues at Stanford are specifically engineered by any means necessary to have exotic quantum properties like high temperature superconductivity. My materials are arguably among the most exotic grown at Stanford, and yet they grow naturally all over the world.

Unfortunately, these crystals are currently found in waste tailings of copper mines in the Atacama desert, a cruel irony of over-extraction. My main project now is to study natural specimen and to help improve desert conditions from both an anthropological and geological perspective. Water rights remain a key issue in the Atacama, and unfortunately, mining practices have greatly elevated local arsenic levels, among other concerns. My dream is that in helping to clean up the desert that I can learn something about the future of quantum computing.

I don't update this profile very much. Please see my linked website to follow my work!

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  • Phonon dynamics in quantum spin liquid and valence bond crystal states in the barlowite family of kagome magnets PHYSICAL REVIEW B Campello, A. C., Wen, J., Cai, Y. Q., Breidenbach, A. T., Smaha, R. W., Jiang, H., Lee, Y. S. 2025; 111 (9)

    View details for DOI 10.1103/PhysRevB.111.094406

    View details for Web of Science ID 001457207700001

  • Halide Perovskites Breathe Too: The Iodide-Iodine Equilibrium and Self-Doping in Cs2SnI6. ACS central science Vigil, J. A., Wolf, N. R., Slavney, A. H., Matheu, R., Saldivar Valdes, A., Breidenbach, A., Lee, Y. S., Karunadasa, H. I. 2024; 10 (4): 907-919

    Abstract

    The response of an oxide crystal to the atmosphere can be personified as breathing-a dynamic equilibrium between O2 gas and O2- anions in the solid. We characterize the analogous defect reaction in an iodide double-perovskite semiconductor, Cs2SnI6. Here, I2 gas is released from the crystal at room temperature, forming iodine vacancies. The iodine vacancy defect is a shallow electron donor and is therefore ionized at room temperature; thus, the loss of I2 is accompanied by spontaneous n-type self-doping. Conversely, at high I2 pressures, I2 gas is resorbed by the perovskite, consuming excess electrons as I2 is converted to 2I-. Halide mobility and irreversible halide loss or exchange reactions have been studied extensively in halide perovskites. However, the reversible exchange equilibrium between iodide and iodine [2I-(s) ↔ I2(g) + 2e-] described here has often been overlooked in prior studies, though it is likely general to halide perovskites and operative near room temperature, even in the dark. An analysis of the 2I-(s)/I2(g) equilibrium thermodynamics and related transport kinetics in single crystals of Cs2SnI6 therefore provides insight toward achieving stable composition and electronic properties in the large family of iodide perovskite semiconductors.

    View details for DOI 10.1021/acscentsci.4c00056

    View details for PubMedID 38680557

    View details for PubMedCentralID PMC11046464

  • Halide Perovskites Breathe Too: The Iodide-Iodine Equilibrium and Self-Doping in Cs<sub>2</sub>SnI<sub>6</sub> ACS CENTRAL SCIENCE Vigil, J. A., Wolf, N. R., Slavney, A. H., Matheu, R., Saldivar Valdes, A., Breidenbach, A., Lee, Y. S., Karunadasa, H. I. 2024

    View details for DOI 10.1021/acscentsci.4c00056

    View details for Web of Science ID 001196483400001

  • High-energy spin excitations in the quantum spin liquid candidate Zn-substituted barlowite probed by resonant inelastic x-ray scattering PHYSICAL REVIEW B Smaha, R. W., Pelliciari, J., Jarrige, I., Bisogni, V., Breidenbach, A. T., Jiang, J., Wen, J., Jiang, H., Lee, Y. S. 2023; 107 (6)

    View details for DOI 10.1103/PhysRevB.107.L060402

    View details for Web of Science ID 000938787400002

  • Charge Reservoirs in an Expanded Halide Perovskite Analog: Enhancing High-Pressure Conductivity through Redox-Active Molecules. Angewandte Chemie (International ed. in English) Matheu, R., Ke, F., Breidenbach, A., Wolf, N., Lee, Y., Liu, Z., Leppert, L., Lin, Y., Karunadasa, H. 2022

    Abstract

    As halide perovskites and their derivatives are being developed for numerous optoelectronic applications, controlling their electronic doping remains a fundamental challenge. Herein, we describe a novel strategy of using redox-active organic molecules as stoichiometric electron acceptors. The cavities in the new expanded perovskite analogs (dmpz)[Sn2X6], (X = Br- ( 1Br ) or I- ( 1I )) are occupied by dmpz2+ (N, N'-dimethylpyrazinium), with the LUMOs lying ca. 1 eV above the valence band maximum (VBM). Compressing the metal-halide framework drives up the VBM in 1I relative to the dmpz LUMO. The electronic conductivity increases by a factor of 105 with pressure, reaching 50(17) S cm-1 at 60 GPa, exceeding the high-pressure conductivities of most halide perovskites. This conductivity enhancement is attributed to an increased hole density created by dmpz2+ reduction. This work elevates the role of organic cations in 3D metal-halides, from templating the structure to serving as charge reservoirs for tuning the carrier concentration.

    View details for DOI 10.1002/anie.202202911

    View details for PubMedID 35421260

  • Anomalous Nernst and Seebeck coefficients in epitaxial thin film Co2MnAlxSi1-x and Co2FeAl PHYSICAL REVIEW B Breidenbach, A. T., Yu, H., Peterson, T. A., McFadden, A. P., Peria, W. K., Palmstrom, C. J., Crowell, P. A. 2022; 105 (14)

    View details for DOI 10.1103/PhysRevB.105.144405

    View details for Web of Science ID 000804069200004

https://orcid.org/0000-0001-6866-0679