Regensburg 2022 – scientific programme
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TT: Fachverband Tiefe Temperaturen
TT 23: Frustrated Magnets - General
TT 23.4: Talk
Wednesday, September 7, 2022, 15:45–16:00, H22
Spin excitations in the frustrated helimagnet FeP — •Aleksandr Sukhanov, Yuliia Tymoshenko, Anton Kulbakov, and Dmytro Inosov — Institut für Festkörper- und Materialphysik, Technische Universität Dresden, D-01069 Dresden
The metallic compound FeP belongs to the class of materials that feature a complex noncollinear spin order driven by the magnetic frustration. While its double-helix magnetic structure with a period λs ≈ 5c, where c is the lattice constant, was previously well determined, the relevant spin-spin interactions that lead to that ground state remain unknown. By performing extensive inelastic neutron scattering measurements, we obtained the spin-excitation spectra in a large part of the momentum-energy space. The spectra show that the magnons are gapped with a gap energy of ∼5 meV. Despite the 3D crystal structure, the magnon modes display strongly anisotropic dispersions, revealing quasi-one-dimensional character of the magnetic interactions in FeP. The physics of the material, however, is not determined by the dominating exchange, which is ferromagnetic. Instead, the weaker two-dimensional antiferromagnetic interactions between the rigid ferromagnetic spin chains drive the magnetic frustration. Using linear spin-wave theory, we were able to construct an effective Heisenberg Hamiltonian with an anisotropy term capable of reproducing the observed spectra. This enabled us to quantify the exchange interactions in FeP and determine the mechanism of its magnetic frustration.