@article{prodan_easy-cone_2025,

title = {Easy-cone state mediating the spin reorientation in the topological kagome magnet Fe_{3}Sn_{2}},

author = {L. Prodan and D. M. Evans and A. S. Sukhanov and S. E. Nikitin and A. A. Tsirlin and L. Puntigam and M. C. Rahn and L. Chioncel and V. Tsurkan and I. Kézsmárki},

url = {https://link.aps.org/doi/10.1103/PhysRevB.111.184442},

doi = {10.1103/PhysRevB.111.184442},

year  = {2025},

date = {2025-05-30},

urldate = {2025-05-30},

journal = {Phys. Rev. B},

volume = {111},

number = {18},

pages = {184442},

abstract = {We investigated temperature-driven spin reorientation (SR) in the itinerant kagome magnet Fe3⁢Sn2 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 ∼40 and 130 K through an intermediate easy-cone (or tilted spin) state. This state, induced by the interplay between the anisotropy constants 𝐾1 and 𝐾2, is clearly manifested in the thermal evolution of the magnetic structure factor, which reveals a gradual change of the SR angle 𝜃 between 40 and 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. Our analysis suggests that the SR and associated microstructural transformations are the results of competing first- and second-order anisotropy constants.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{kong_strain_2025,

title = {Strain Engineering of Magnetic Anisotropy in the Kagome Magnet Fe_{3}Sn_{2}},

author = {D. Kong and A. Kovács and M. Charilaou and M. Altthaler and L. Prodan and V. Tsurkan and D. Meier and X. Han and I. Kézsmárki and R. E. Dunin-Borkowski},

url = {https://doi.org/10.1021/acsnano.4c16603},

doi = {10.1021/acsnano.4c16603},

year  = {2025},

date = {2025-02-24},

urldate = {2025-03-01},

journal = {ACS Nano},

volume = {19},

number = {8},

pages = {8142–8151},

abstract = {The ability to control magnetism with strain offers innovative pathways for the modulation of magnetic domain configurations and for the manipulation of magnetic states in materials on the nanoscale. Although the effect of strain on magnetic domains has been recognized since the early work of C. Kittel, detailed local observations have been elusive. Here, we use mechanical strain to achieve reversible control of magnetic textures in a kagome-type Fe3Sn2 ferromagnet without the use of an external electric current or magnetic field in situ in a transmission electron microscope at room temperature. We use Fresnel defocus imaging, off-axis electron holography and micromagnetic simulations to show that tensile strain modifies the structures of dipolar skyrmions and switches the magnetization between out-of-plane and in-plane configurations. We also present quantitative measurements of magnetic domain wall structures and their transformations as a function of strain. Our results demonstrate the fundamental importance of anisotropy effects and their interplay with magnetoelastic and magnetocrystalline energies, providing opportunities for the development of strain-controlled devices for spintronic applications.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{zahn_reversible_2025,

title = {Reversible long-range domain wall motion in an improper ferroelectric},

author = {M. Zahn and A. M. Müller and K. P. Kelley and S. Neumayer and S. V. Kalinin and I. Kézsmarki and M. Fiebig and T. Lottermoser and N. Domingo and D. Meier and J. Schultheiß},

url = {https://doi.org/10.1038/s41467-025-57062-8},

doi = {10.1038/s41467-025-57062-8},

year  = {2025},

date = {2025-02-19},

urldate = {2025-02-19},

journal = {Nat. Commun.},

volume = {16},

number = {1},

pages = {1781},

abstract = {Reversible ferroelectric domain wall movements beyond the 10 nm range associated with Rayleigh behavior are usually restricted to specific defect-engineered systems. Here, we demonstrate that such long-range movements naturally occur in the improper ferroelectric ErMnO3 during electric-field-cycling. We study the electric-field-driven motion of domain walls, showing that they readily return to their initial position after having traveled distances exceeding 250 nm. By applying switching spectroscopy band-excitation piezoresponse force microscopy, we track the domain wall movement with nanometric spatial precision and analyze the local switching behavior. Phase field simulations show that the reversible long-range motion is intrinsic to the hexagonal manganites, linking it to their improper ferroelectricity and topologically protected structural vortex lines, which serve as anchor point for the ferroelectric domain walls. Our results give new insight into the local dynamics of domain walls in improper ferroelectrics and demonstrate the possibility to reversibly displace domain walls over much larger distances than commonly expected for ferroelectric systems in their pristine state, ensuring predictable device behavior for applications such as tunable capacitors or sensors.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{prodan_large_2023,

title = {Large ordered moment with strong easy-plane anisotropy and vortex-domain pattern in the kagome ferromagnet Fe_{3}Sn},

author = {L. Prodan and D. M. Evans and S. M. Griffin and A. Oestlin and M. Altthaler and E. Lysne and I. G. Filippova and S. Shova and L. Chioncel and V. Tsurkan and I. Kézsmárki},

doi = {10.1063/5.0155295},

issn = {0003-6951},

year  = {2023},

date = {2023-07-01},

urldate = {2023-07-01},

journal = {Appl. Phys. Lett.},

volume = {123},

number = {2},

pages = {021901},

abstract = {We report the magnetic anisotropy of kagome bilayer ferromagnet Fe3Sn probed by the bulk magnetometry and magnetic force microscopy (MFM) on high-quality single crystals. The dependence of magnetization on the orientation of the external magnetic field reveals strong easyplane magnetocrystalline anisotropy and anisotropy of the saturation magnetization. The leading magnetocrystalline anisotropy constant shows a monotonous increase from K-1 approximate to -1.0 x 10(6) J/m(3) at 300K to -1.3 x 10(6) J/m(3) at 2K. Our ab initio electronic structure calculations yield the value of total magnetic moment of 7.1 mu(B)=f.u. and a magnetocrystalline anisotropy energy density of -0.57meV=f.u. (-1.62 x 10(6)J/m(3)) both being in reasonable agreement with the experimental values. The MFM imaging reveals micrometer-scale magnetic vortices with weakly pinned cores that vanish at the saturation field of similar to 3T applied perpendicular to the kagome plane. The observed vortex-domain structure is well reproduced by the micromagnetic simulations, using the experimentally determined value of the anisotropy and exchange stiffness. (c) 2023 Author(s).},

keywords = {},

pubstate = {published},

tppubtype = {article}

}