Topological insulator in a helicoidal magnetization field
arXiv:1611.00642 · doi:10.1103/PhysRevB.94.174436
Abstract
A key feature of topological insulators is the robustness of the electron energy spectrum. At a surface of a topological insulator, Dirac point is protected by the characteristic symmetry of the system. The breaking of the symmetry opens a gap in the energy spectrum. Therefore, topological insulators are very sensitive to magnetic fields, which can open a gap in the electronic spectrum. Concerning "internal" magnetic effects, for example the situation with doped magnetic impurities, is not trivial. A single magnetic impurity is not enough to open the band gap, while in the case of a ferromagnetic chain of deposited magnetic impurities the Dirac point is lifted. However, a much more interesting case is when localized magnetic impurities form a chiral spin order. Our first principle density functional theory calculations have shown that this is the case for Fe deposited on the surface of Bi2Se3 topological insulator. But not only magnetic impurities can form a chiral helicoidal spin texture. An alternative way is to use chiral multiferroics (prototype material is LiCu2O2) that induce a proximity effect. The theoretical approach we present here is valid for both cases. We observed that opposite to a ferromagnetically ordered case, a chiral spin order does not destroy the Dirac point. We also observed that the energy gap appears at the edges of the new Brillouin zone. Another interesting result concerns the spin dynamics. We derived an equation for the spin density dynamics with a spin current and relaxation terms. We have shown that the motion of the conductance electron generates a magnetic torque and exerts a certain force on the helicoidal texture.
arXiv comment10 pages, 10 figures, accepted for publication in Phys. Rev. B
References in corpus (25)
- Topological Insulators
- Topological insulators and superconductors
- Superconducting proximity effect and Majorana fermions at the surface of a topological insulator
- Anomalous Hall effect
- Topological Insulators with Inversion Symmetry
- Majorana Fermions and a Topological Phase Transition in Semiconductor-Superconductor Heterostructures
- A generic new platform for topological quantum computation using semiconductor heterostructures
- Multiferroics: different ways to combine magnetism and ferroelectricity
- Magnetic impurities on the surface of a topological insulator
- A topological insulator surface under strong Coulomb, magnetic and disorder perturbations
- Theory of the anomalous Hall effect from the Kubo formula and the Dirac equation
- Vector chiral and multipolar orders in the spin-1/2 frustrated ferromagnetic chain in magnetic field
- Ordering of magnetic impurities and tunable electronic properties of topological insulators
- Incommensurate spin correlations in Heisenberg spin-1/2 zig-zag ladders
- Numerical and approximate analytical results for the frustrated spin-1/2 quantum spin chain
- Topological Josephson -junctions
- Switching the Ferroelectric Polarization by External Magnetic Fields in the Spin = 1/2 Chain Cuprate LiCuVO4
- Finite-temperature dynamical magnetic susceptibility of quasi-one-dimensional frustrated spin-1/2 Heisenberg antiferromagnets
- Signatures of Dirac fermion-mediated magnetic order
- Thermodynamics of multiferroic spin chains
- Self-consistent theory of ferromagnetism on the surface of a topological insulator
- Numerical solution of the relativistic single-site scattering problem for the Coulomb and the Mathieu potential
- Spin Helix of Magnetic Impurities in Two-dimensional Helical Metal
- Magnetization dynamics and Majorana fermions in ferromagnetic Josephson junctions along the quantum spin Hall edge
- Anisotropic surface transport in topological insulators in proximity to a helical spin density wave