Ordering governs magnetic tunability in FePt-based Janus particles independent of curvature
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| Main Authors: | , , , , , , , , |
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| Format: | Preprint |
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2026
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| _version_ | 1866918497808809984 |
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| author | Gonzalez-Vazquez, Natalia Suadiye, Eylül Goering, Eberhard Miranda-Rosales, Ruben O. David, Hilda Thiele, Frank Unangst, Julia Schulz, Andrew K. Richter, Gunther |
| author_facet | Gonzalez-Vazquez, Natalia Suadiye, Eylül Goering, Eberhard Miranda-Rosales, Ruben O. David, Hilda Thiele, Frank Unangst, Julia Schulz, Andrew K. Richter, Gunther |
| contents | Magnetic Janus particles enable remote actuation in biomedical, microfluidic, and materials applications. While curvature-driven magnetic effects are well known at the nanoscale, their influence on magnetization reversal in micrometer-sized particles is still unclear. In this work, we combine experiments and micromagnetic simulations to study curvature-dependent magnetism in FePt-coated Janus particles with diameters ranging from 3-10 microm, and extend the analysis to 1-20 microm through simulations. Structural and crystallographic characterization confirms continuous FePt coatings with near-equiatomic composition and partial L1_0 ordering. Magnetometry measurements show nearly unchanged hysteresis behavior across particle sizes, with coercivity remaining approximately constant m_0Hc = 1.13 +/- 0.05 T, pooled n = 8). Statistical analysis reveals no significant dependence of coercivity or remanence on particle diameter (p = 0.61 for Hc and p = 0.85 for Mr/Ms). To explain these results, we introduce FunMaP, an open-source micromagnetic simulation framework that enables direct comparison between experiments and idealized FePt caps. Simulations confirm that curvature has little effect on magnetization reversal at micrometer scales, consistent with a locally planar magnetic limit where the exchange length is much smaller than the particle radius. In contrast, differences in chemical ordering strongly affect hysteresis shape and coercivity. These findings demonstrate that magnetic behavior in micrometer-scale FePt Janus particles is governed mainly by material ordering rather than curvature. This work establishes a quantitative boundary for curvature-dependent magnetism and provides design guidelines for programmable magnetic micro-systems. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2605_12283 |
| institution | arXiv |
| publishDate | 2026 |
| record_format | arxiv |
| spellingShingle | Ordering governs magnetic tunability in FePt-based Janus particles independent of curvature Gonzalez-Vazquez, Natalia Suadiye, Eylül Goering, Eberhard Miranda-Rosales, Ruben O. David, Hilda Thiele, Frank Unangst, Julia Schulz, Andrew K. Richter, Gunther Materials Science Mesoscale and Nanoscale Physics Magnetic Janus particles enable remote actuation in biomedical, microfluidic, and materials applications. While curvature-driven magnetic effects are well known at the nanoscale, their influence on magnetization reversal in micrometer-sized particles is still unclear. In this work, we combine experiments and micromagnetic simulations to study curvature-dependent magnetism in FePt-coated Janus particles with diameters ranging from 3-10 microm, and extend the analysis to 1-20 microm through simulations. Structural and crystallographic characterization confirms continuous FePt coatings with near-equiatomic composition and partial L1_0 ordering. Magnetometry measurements show nearly unchanged hysteresis behavior across particle sizes, with coercivity remaining approximately constant m_0Hc = 1.13 +/- 0.05 T, pooled n = 8). Statistical analysis reveals no significant dependence of coercivity or remanence on particle diameter (p = 0.61 for Hc and p = 0.85 for Mr/Ms). To explain these results, we introduce FunMaP, an open-source micromagnetic simulation framework that enables direct comparison between experiments and idealized FePt caps. Simulations confirm that curvature has little effect on magnetization reversal at micrometer scales, consistent with a locally planar magnetic limit where the exchange length is much smaller than the particle radius. In contrast, differences in chemical ordering strongly affect hysteresis shape and coercivity. These findings demonstrate that magnetic behavior in micrometer-scale FePt Janus particles is governed mainly by material ordering rather than curvature. This work establishes a quantitative boundary for curvature-dependent magnetism and provides design guidelines for programmable magnetic micro-systems. |
| title | Ordering governs magnetic tunability in FePt-based Janus particles independent of curvature |
| topic | Materials Science Mesoscale and Nanoscale Physics |
| url | https://arxiv.org/abs/2605.12283 |