Easy-cone state mediating the spin reorientation in topological kagome magnet Fe$_3$Sn$_2$

L. Prodan; D. M. Evans; A. S. Sukhanov; S. E. Nikitin; A. A. Tsirlin; L. Puntingam; M. C. Rahn; L. Chioncel; V. Tsurkan; I. Kezsmarki

arXiv · 2502.03239

Easy-cone state mediating the spin reorientation in topological kagome magnet Fe$_3$Sn$_2$

L. Prodan·D. M. Evans·A. S. Sukhanov·S. E. Nikitin·A. A. Tsirlin·L. Puntingam·M. C. Rahn·L. Chioncel·V. Tsurkan·I. Kezsmarki

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Abstract

We investigated temperature-driven spin reorientation (SR) in the itinerant kagome magnet Fe$_3$Sn$_2$ using high-resolution synchrotron x-ray diffraction, neutron diffraction, magnetometry, and magnetic force microscopy (MFM), further supported by phenomenological analysis. Our study reveals a crossover from the state with easy-plane anisotropy to the high-temperature state with uniaxial easy-axis anisotropy taking place between $\sim40-130$~ K through an intermediate easy-cone (or tilted spin) state. This state, induced by the interplay between the anisotropy constants $K_1$ and $K_2$, is clearly manifested in the thermal evolution of the magnetic structure factor, which reveals a gradual change of the SR angle $\mathbf{\theta}$ between $40-130$~K. We also found that the SR is accompanied by a magnetoelastic effect. Zero-field MFM images across the SR range show a transformation in surface magnetic patterns from a dendritic structure at 120~K, to domain wall dominated MFM contrast at 40~K.

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L. Prodan, D. M. Evans, A. S. Sukhanov, S. E. Nikitin, A. A. Tsirlin, L. Puntingam, M. C. Rahn, L. Chioncel, V. Tsurkan, I. Kezsmarki. 2025-02-05. Easy-cone state mediating the spin reorientation in topological kagome magnet Fe$_3$Sn$_2$. https://arxiv.org/abs/2502.03239

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