Quantum Lifshitz Point

I study a quantum Lifshitz point in a three-dimensional itinerant antiferromagnet, in particular the scaling of the N\'{e}el temperature, the correlation length, the staggered susceptibility, the specific heat coefficient and the resistivity. At low temperatures, the model is shown to have the inverse staggered susceptibility and the resistivity varying as T$^{5/4}$, and the specific heat coefficient varying as T$^{1/4}$

Zeeman spin-orbit coupling in antiferromagnetic conductors

This article is a brief review of Zeeman spin-orbit coupling, arising in a low-carrier commensurate N\'eel antiferromagnet subject to magnetic field. The field tends to lift the degeneracy of the electron spectrum. However, a hidden symmetry protects double degeneracy of Bloch eigenstates at special momenta in the Brillouin zone. The effective transverse $g$-factor vanishes at such points, thus acquiring a substantial momentum dependence, which turns a textbook Zeeman term into a spin-orbit coupling. After describing the symmetry underpinnings of the Zeeman spin-orbit coupling, I compare it with its intrinsic counterparts such as Rashba coupling, and then show how Zeeman spin-orbit coupling may survive in the presence of intrinsic spin-orbit coupling. Finally, I outline some of the likely experimental manifestations of Zeeman spin-orbit coupling, and compare it with similar phenomena in other settings such as semiconducting quantum wells.Comment: Review article for the topical issue on Spin-Orbit-Coupled Materials of the Journal of Physics and Chemistry of Solid

Electric excitation of spin resonance in antiferromagnetic conductors

Antiferromagnetism couples electron spin to its orbital motion, thus allowing excitation of electron-spin transitions by an ac electric rather than magnetic field - with absorption, exceeding that of common electron spin resonance at least by four orders of magnitude. In addition to potential applications in spin electronics, this phenomenon may be used as a spectroscopy to study antiferromagnetic materials of interest - from chromium to borocarbides, cuprates, iron pnictides, and organic and heavy fermion conductors.Comment: the journal print versio

Diagnosing a strong topological insulator by quantum oscillations

We show how quantum oscillation measurements of surface states in an insulator may allow to diagnose a strong topological insulator and distinguish it from its weak or topologically trivial counterpart. The criterion is defined by the parity of the number of fundamental frequencies in the surface-state quantum oscillation spectrum: an even number of frequencies implies a weak or a topologically trivial insulator, whereas an odd number points to a strong topological insulator. We also discuss various aspects and issues related to applying this criterion in practice.Comment: 5.5 pages, 2 figure

Local injection of pure spin current generates electric current vortices

We show that local injection of pure spin current into an electrically disconnected ferromagnetic - normal-metal sandwich induces electric currents, that run along closed loops inside the device, and are powered by the source of the spin injection. Such electric currents may significantly modify voltage distribution in spin-injection devices and induce long-range tails of spin accumulation.Comment: Journal version. Improved notation, suggestions for experimental observation adde

Acceleration of Plasmoids in Waveguides by a Superhigh-Frequency Wave

Acceleration of plasmoids in waveguides by superhigh-frequency electromagnetic wav

Electron states, bound to a texture in a N\'eel antiferromagnet

We study electron states, bound to topological textures such as skyrmions and domain walls in a N\'eel antiferromagnet. In certain limits, we find the dependence of bound states on the geometry of the texture, and estimate the bound-state contribution to its energy. This contribution proves significant compared with the purely magnetic energy, and substantially affects the equilibrium geometry of the texture. The bound-state contribution also induces a large shift of the transition line between the modulated and the uniform phase, extending the latter.Comment: 20 pages, 15 figures, 3 appendices, 36 reference

Kramers degeneracy in a magnetic field and Zeeman spin-orbit coupling in antiferromagnets

In this article, I analyze the symmetries and degeneracies of electron eigenstates in a commensurate collinear antiferromagnet. In a magnetic field transverse to the staggered magnetization, a hidden anti-unitary symmetry protects double degeneracy of the Bloch eigenstates at a special set of momenta. In addition to this `Kramers degeneracy' subset, the manifold of momenta, labeling the doubly degenerate Bloch states in the Brillouin zone, may also contain an `accidental degeneracy' subset, that is not protected by symmetry and that may change its shape under perturbation. These degeneracies give rise to a substantial momentum dependence of the transverse g-factor in the Zeeman coupling, turning the latter into a spin-orbit interaction. I discuss a number of materials, where Zeeman spin-orbit coupling is likely to be present, and outline the simplest properties and experimental consequences of this interaction, that may be relevant to systems from chromium to borocarbides, cuprates, hexaborides, iron pnictides, as well as organic and heavy fermion conductors.Comment: 16+ pages, extended version of arXiv:0805.0378; revised versio