We report strong unidirectional anisotropy in bulk polycrystalline B20 FeGe measured by ferromagnetic resonance spectroscopy. Bulk and micron sized samples were produced and analytically characterized. FeGe is a B20 compound with inherent Dzyaloshinskii-Moriya interaction. Lorenz microscopy confirms a skyrmion lattice at 190 K in a magnetic field of 150 mT. Ferromagnetic resonance was measured at 276 K ± 1 K, near the Curie temperature. Two resonance modes were observed, both exhibit a unidirectional anisotropy of K = 1153 J/m 3 ± 10 J/m 3 in the primary, and K = 28 J/m 3 ± 2 J/m 3 in the secondary mode, previously unknown in bulk ferromagnets.Additionally, about 25 standing spin wave modes are observed inside a micron sized FeGe wedge, measured at room temperature (∼ 293 K). These modes also exhibit unidirectional anisotropy.

Magnetic annealing of the collinear antiferromagnet PdMn with excess Pd produces strongly pinned magnetic moments in the annealing field direction. This behaviour can be understood with the help of the magnetic-field-biased diffusion model. Here, the magnetic field creates an energy difference between the two possible occupations of the antiferromagnetic Mn-sublattices by the Pdexcess atoms. This, mediated by diffusion, leads to an imbalance in the amount of the Pd-excess atoms in these sublattices and, subsequently, to an imbalance in the total magnetization of the sublattices. We investigate this effect's dependence on the annealing field, time, and temperature. The results are then compared to the results of the magnetic-field-biased diffusion model, which gives good agreement.

The shell-ferromagnetic effect originates from the segregation process in off-stoichiometric Ni–Mn-based Heusler.