Surface ferromagnetism as a basis for the creation of planar metamaterials

In this work, we study the influence of the surface on the energy of spin excitations of a ferromagnetic crystal in the Heisenberg model, with a particular focus on the possibility of using this effect to create planar metamaterials.

The Internal Field in a Ferromagnetic Crystal with Chiral Molecular Packing of Achiral Organic Radicals

The achiral organic radical dinitrophenyl nitronyl nitroxide crystallizes in two enantiomorphs, both being chiral tetragonal space groups that are mirror images of each other. Muon-spin rotation experiments have been performed to study the magnetic properties of these crystals and demonstrate that long-range magnetic order is established below a temperature of 1.10(1) K. Two oscillatory components are detected in the muon data, which show two different temperature dependences.

Одноионный механизм слабого антиферромагнетизма и спин-флоп-переход в двухподрешеточном ферромагнетике

The ground state of a Heisenberg ferromagnet with noncollinear single-ion anisotropy axes of two sublattices is investigated in the external magnetic field applied in the anisotropy axes plane. The noncollinearity of local anisotropy axes leads to new effect - the first order spin reorientation phase transition of the spin-flop type. The transition field depends on the value of anisotropy and orientation of the sublattice axes. Stability analysis of magnetic states shown that the field induced transition is accompanied by the magnetization hysteresis. The dependencies of the spin-flop transition field, the magnetization jump value and the susceptibility on the anisotropy parameters are determined. The obtained results are used for explanation of the magnetization field dependence in the ferromagnetic crystal PbMnBO_4.

Magnetic Weyl semimetal phase in a Kagomé crystal

Weyl semimetals are crystalline solids that host emergent relativistic Weyl fermions and have characteristic surface Fermi-arcs in their electronic structure. Weyl semimetals with broken time reversal symmetry are difficult to identify unambiguously. In this work, using angle-resolved photoemission spectroscopy, we visualized the electronic structure of the ferromagnetic crystal Co3Sn2S2 and discovered its characteristic surface Fermi-arcs and linear bulk band dispersions across the Weyl points. These results establish Co3Sn2S2 as a magnetic Weyl semimetal that may serve as a platform for realizing phenomena such as chiral magnetic effects, unusually large anomalous Hall effect and quantum anomalous Hall effect.