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Fe
O
Lenander, E. Y.*; Nielsen, F. B.*; Lass, J.*; Hansen, U. B.*; Krighaar, K. M. L.*; Preuss, A.*; Weber, T.*; Enderle, M.*; Jacobsen, H.*; Stuhr, U.*; et al.
Physical Review B, 113(1), p.014424_1 - 014424_14, 2026/01
被引用回数：0The frustrated magnet BiFeO has been reported to exhibit complex spin dynamics coexisting with conventional spin wave excitations. The magnetic Fe
(
) ions are arranged into a distorted two-dimensional Cairo pentagonal lattice with weak couplings between the layers, developing long-ranged noncollinear antiferromagnetic order below 245 K. In order to enable studies and modeling of the complex dynamics close to 
, we have reexamined the magnetic excitations across the complete energy scale (
meV) at 10 K. We discover two distinct gaps, which can be explained by introducing, respectively, easy axis and easy plane anisotropy on the two unequivalent Fe sites. We develop a refined spin Hamiltonian that accurately accounts for the dispersion of essentially all spin-wave branches across the full spectral range, except around 40 meV, where a splitting and dispersion are observed. Polarization analysis shows that the system has magnetic anisotropic fluctuations, consistent with our model. A continuum of scattering is observed above the spin wave branches and is found to principally be explained by an instrumental resolution effect. The full experimental mapping of the excitation spectrum and the refined spin Hamiltonian provides a foundation for future quantitative studies of spin waves coexisting with unconventional magnetic fluctuations in this frustrated magnet found at higher temperatures.
studied by polarized and unpolarized neutron diffraction寺田 典樹*; Qureshi, N.*; Stunault, A.*; Enderle, M.*; Ouladdiaf, B.*; Colin, C. V.*; Khalyavin, D. D.*; Manuel, P.*; Orlandi, F.*; 宮原 慎*; et al.
Physical Review B, 102(8), p.085131_1 - 085131_7, 2020/08
被引用回数：4 パーセンタイル：17.82(Materials Science, Multidisciplinary)We have determined the magnetic structures in high pressure phase with the giant ferroelectric polarization in DyMnO. For Mn spins, the E-type magnetic ordering is stabilized above 4.0 GPa, which induces the giant ferroelectric polarization through the exchange striction effect. Furthermore, we have elucidate that the lattice distortion generated through the exchange striction for the Dy and Mn bonds can give the significant magnetic field enhancement of ferroelectric polarization in this system.
南部 雄亮*; Barker, J.*; 沖野 夕貴*; 吉川 貴史*; 塩見 雄毅*; Enderle, M.*; Weber, T.*; Winn, B.*; Graves-Brook, M.*; Tranquada, J. M.*; et al.
Physical Review Letters, 125(2), p.027201_1 - 027201_6, 2020/07
被引用回数：78 パーセンタイル：95.16(Physics, Multidisciplinary)We measure the mode-resolved direction of the precessional motion of the magnetic order, i.e., magnon polarization, via the chiral term of inelastic polarized neutron scattering spectra. The magnon polarization is a unique and unambiguous signature of magnets and is important in spintronics, affecting thermodynamic properties such as the magnitude and sign of the spin Seebeck effect. However, it has never been directly measured in any material until this work. The observation of both signs of magnon polarization in Y
Fe
O
also gives direct proof of its ferrimagnetic nature. The experiments agree very well with atomistic simulations of the scattering cross section.
