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Anomalous Hall effect in thin films of the kagome ferromagnet Fe₃Sn₂
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Anomalous Hall effect in thin films of the kagome ferromagnet Fe₃Sn₂

Tarush Tandon
Master of Science (M.S.), Drexel University
Sep 2025
DOI:
https://doi.org/10.17918/00011202
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Abstract

Anomalous Hall effect Kagome ferromagnets Triiron ditin intermetallic compounds Thin Films
In recent times, quantum topological materials have garnered significant attention in the fields of energy-efficient electronics, spintronics, and even quantum computing. The topological kagome magnet Fe₃Sn₂ hosts interesting features such as van Hove singularities, flat bands, and Dirac cones in its electronic band structure. In bulk, Fe₃Sn₂ is described as a non-collinear frustrated soft ferromagnet with a reported Curie temperature of 640 K, with spins oriented parallel to the c-axis of the lattice at 300 K. There have been several reports on the Berry-phase induced (intrinsic) giant anomalous Hall effect (AHE) in Fe₃Sn₂ with an anomalous Hall resistivity of ~5 [mu][omega]cm in bulk single crystals, which is almost 20 times greater than that in traditional ferromagnets like Fe and Ni. In this work, I investigate the AHE in thin films of Fe₃Sn₂ of varying thicknesses grown on (0001) -- oriented Al₂O₃ substrates with an Fe (110) buffer layer via molecular beam epitaxy (MBE). The AHE effect is known to have both intrinsic and extrinsic factors contributing to its origin in ferromagnets. It has been shown that the anomalous Hall resistivity ([rho]Axy) arising from both contributions demonstrates a strong dependence on the longitudinal resistivity ([rho]xx) of the material. Recently, a theory unifying both intrinsic and extrinsic contributions to the AHE in ferromagnets has been proposed. In this work, I will demonstrate the epitaxial and continuous growth of crystalline thin films of Fe₃Sn₂ of high phase purity via MBE, supported by X-ray diffraction and reflectivity measurements. Furthermore, using data collected from magnetometry experiments, I will investigate the thickness-dependent behavior of the magnetization of the samples. In addition, with the help of my results from electronic transport measurements, I will demonstrate that [rho]xx of Fe₃Sn₂ films can be controlled by varying the film thickness. I will illustrate the longitudinal conductivity-dependent behavior of the anomalous Hall conductivity of these films in the context of the unified AHE theory of ferromagnets, exhibiting both intrinsic and extrinsic origins.

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