Antiferromagnetic skyrmion crystals in the Rashba Hund’s insulator on triangular lattice

Abstract

Motivated by the importance of antiferromagnetic skyrmions as building blocks of next-generation data storage and processing devices, we report theoretical and computational analysis of a model for a spin-orbit coupled correlated Hund’s insulator magnet on a triangular lattice. We find that two distinct antiferromagnetic skyrmion crystal (AF-SkX) states can be stabilized at low temperatures in the presence of external magnetic field. The results are obtained via Monte Carlo simulations on an effective magnetic model derived from the microscopic electronic Hamiltonian consisting of Rashba spin-orbit coupling, as well as strong Hund’s coupling of electrons to classical spins at half-filling. The two AF-SkX phases are understood to originate from a classical spin liquid state that exists at low but finite temperatures. These AF-SkX states can be easily distinguished from each other in experiments as they are characterized by peaks at distinct momenta in the spin structure factor which is directly measured in neutron scattering experiments. We also discuss examples of materials where the model as well as the two AF-SkX states can be realized.

Skyrmion crystal and spiral phases in centrosymmetric bilayer magnets with staggered Dzyaloshinskii-Moriya interaction

“…In this sense, this state is qualitatively different from the sublatticedependent SkXs in previous studies, which have nonzero scalar chirality in the whole system. [112][113][114][115][116][117][118][119][120][121] In addition, the present SkX is also different from the antiferromagnetic SkX parametrized by the Nèel order describing the bipartite magnetic lattice. 100,101,[108][109][110][111] The appearance of the AF-SkX is due to the synergy among D, A ion , J ∥ , and H in the model in Eq.…”

“…This AF-SkX is qualitatively different from the previous antiferromagnetic SkX stabilized at zero field 100,101,[108][109][110][111] and sublattice-dependent SkX with a uniform scalar chirality. [112][113][114][115][116][117][118][119][120][121] We also find that two ferri-type SkX (Ferri-SkX) phases, which consist of the skyrmion layer and topologically-trivial magnetic layer, appear in the vicinity of the AF-SkX phase. Our results provide a way of realizing the AF-SkX by applying the magnetic field far from zero magnetic field, which will stimulate further experimental observations of exotic topological spin crystals beyond the conventional SkX.…”

Effective spin model in momentum space: Toward a systematic understanding of multiple-$Q$ instability by momentum-resolved anisotropic exchange interactions

“…Similar momentum-resolved spin models can be derived from other itinerant electron models. For example, the classical Kondo lattice model in the strong exchange coupling regime (double exchange model [117,118]) is mapped onto the effective spin model with the shortrange spin interactions [119][120][121][122] When taking into account the Rashba-or Dresselhaus-type SOC, the shortrange spin interactions become anisotropic [84,[123][124][125][126][127]. Furthermore, the effective spin model with the shortrange spin interactions can be constructed based on the Hubbard model with the SOC [124,128,129].…”

Effective spin model in momentum space: Toward a systematic understanding of multiple-Qinstability by momentum-resolved anisotropic exchange interactions

“…For example, the classical Kondo lattice model in the strong exchange coupling regime (double exchange model [129,130]) is mapped onto the effective spin model with the short-range spin interactions [131][132][133][134]. When taking into account the Rashbaor Dresselhaus-type SOC, the short-range spin interactions become anisotropic [88,[135][136][137][138][139]. Furthermore, the effective spin model with the short-range spin interactions can be constructed based on the Hubbard model with the SOC [136,140,141].…”