article published yes Eavan Fitzgerald author 2df8ab8f-080d-11ed-979a-bfe651ca3afa Cécile Clavaud author 5f654c5d-04a1-11eb-ab36-ba9ffec58bd80000-0002-1843-3803 Debasish Das author Isaac C Lenton author a550210f-223c-11ec-8182-e2d45e817efb0000-0002-5010-6984 Scott R Waitukaitis author 3A1FFC16-F248-11E8-B48F-1D18A9856A870000-0002-2299-3176 ScWa department MixQUIckR: Mixing with QUIncke Rollers project Tribocharge: a multi-scale approach to an enduring problem in physics project We report on an experimental active matter system with motion restricted to four cardinal directions. Our particles are magnetite-doped colloidal spheres driven by the Quincke electrorotational instability. The absence of a magnetic field (|𝑩|=0) leads to circular trajectories interspersed with short spontaneous runs. Intermediate fields (|𝑩|≲20mT) linearize the motion along the axis perpendicular to 𝑩. At high magnetic fields, we observe the surprising emergence of a second, distinct linearization along the axis parallel to 𝑩. With numerical simulations, we show that this behavior can be explained by anisotropic magnetic susceptibility. https://research-explorer.ista.ac.at/download/20847/20862/2025_PhysReviewE_Fitzgerald.pdf application/pdfno https://creativecommons.org/licenses/by/4.0/ American Physical Society2025 eng 2470-0045 2470-0053 2508.0564310.1103/1ss8-31rb 1126 Fitzgerald, Eavan, Cécile Clavaud, Debasish Das, Isaac C Lenton, and Scott R Waitukaitis. “Rolling at Right Angles: Magnetic Anisotropy Enables Dual-Anisotropic Active Matter.” <i>Physical Review E</i>. American Physical Society, 2025. <a href="https://doi.org/10.1103/1ss8-31rb">https://doi.org/10.1103/1ss8-31rb</a>. Fitzgerald, Eavan, et al. “Rolling at Right Angles: Magnetic Anisotropy Enables Dual-Anisotropic Active Matter.” <i>Physical Review E</i>, vol. 112, no. 6, 065418, American Physical Society, 2025, doi:<a href="https://doi.org/10.1103/1ss8-31rb">10.1103/1ss8-31rb</a>. E. Fitzgerald, C. Clavaud, D. Das, I. C. Lenton, and S. R. Waitukaitis, “Rolling at right angles: Magnetic anisotropy enables dual-anisotropic active matter,” <i>Physical Review E</i>, vol. 112, no. 6. American Physical Society, 2025. E. Fitzgerald, C. Clavaud, D. Das, I.C. Lenton, S.R. Waitukaitis, Physical Review E 112 (2025). Fitzgerald, E., Clavaud, C., Das, D., Lenton, I. C., &#38; Waitukaitis, S. R. (2025). Rolling at right angles: Magnetic anisotropy enables dual-anisotropic active matter. <i>Physical Review E</i>. American Physical Society. <a href="https://doi.org/10.1103/1ss8-31rb">https://doi.org/10.1103/1ss8-31rb</a> Fitzgerald E, Clavaud C, Das D, Lenton IC, Waitukaitis SR. Rolling at right angles: Magnetic anisotropy enables dual-anisotropic active matter. <i>Physical Review E</i>. 2025;112(6). doi:<a href="https://doi.org/10.1103/1ss8-31rb">10.1103/1ss8-31rb</a> Fitzgerald E, Clavaud C, Das D, Lenton IC, Waitukaitis SR. 2025. Rolling at right angles: Magnetic anisotropy enables dual-anisotropic active matter. Physical Review E. 112(6), 065418. 208472025-12-21T23:01:34Z2025-12-29T11:19:34Z