Antiferromagnetic Order in Pauli Limited Unconventional Superconductors

We develop a theory of the coexistence of superconductivity (SC) and antiferromagnetism (AFM) in CeCoIn5. We show that in Pauli-limited nodal superconductors the nesting of the quasi-particle pockets induced by Zeeman pair-breaking leads to incommensurate AFM with the moment normal to the field. We compute the phase diagram and find a first order transition to the normal state at low temperatures, absence of normal state AFM, and coexistence of SC and AFM at high fields, in agreement with experiments. We also predict the existence of a new double-Q magnetic phase

Angular Momentum Transport in Particle and Fluid Disks

We examine the angular momentum transport properties of disks composed of macroscopic particles whose velocity dispersions are externally enhanced (``stirred''). Our simple Boltzmann equation model serves as an analogy for unmagnetized fluid disks in which turbulence may be driven by thermal convection. We show that interparticle collisions in particle disks play the same role as fluctuating pressure forces and viscous dissipation in turbulent disks: both transfer energy in random motions associated with one direction to those associated with another, and convert kinetic energy into heat. The direction of angular momentum transport in stirred particle and fluid disks is determined by the direction of external stirring and by the properties of the collision term in the Boltzmann equation (or its analogue in the fluid problem). In particular, our model problem yields inward transport for vertically or radially stirred disks, provided collisions are suitably inelastic; the transport is outwards in the elastic limit. Numerical simulations of hydrodynamic turbulence driven by thermal convection find inward transport; this requires that fluctuating pressure forces do little to no work, and is analogous to an externally stirred particle disk in which collisions are highly inelastic.Comment: 15 pages; final version accepted by ApJ; minor changes, some clarificatio

Non-equilibrium spin polarization effects in spin-orbit coupling system and contacting metallic leads

We study theoretically the current-induced spin polarization effect in a two-terminal mesoscopic structure which is composed of a semiconductor two-dimensional electron gas (2DEG) bar with Rashba spin-orbit (SO) interaction and two attached ideal leads. The nonequilibrium spin density is calculated by solving the scattering wave functions explicitly within the ballistic transport regime. We found that for a Rashba SO system the electrical current can induce spin polarization in the SO system as well as in the ideal leads. The induced polarization in the 2DEG shows some qualitative features of the intrinsic spin Hall effect. On the other hand, the nonequilibrium spin density in the ideal leads, after being averaged in the transversal direction, is independent of the distance measured from the lead/SO system interface, except in the vicinity of the interface. Such a lead polarization effect can even be enhanced by the presence of weak impurity scattering in the SO system and may be detectable in real experiments.Comment: 6 pages,5 figure

Dynamical magnetic susceptibility in the lamellar cobaltate superconductor Na_xCoO_2⋅y\cdot yH_2O

We systematically analyze the influence of the superconducting gap symmetry and the electronic structure on the dynamical spin susceptibility in superconducting Na_xCoO_2$\cdot y$H_2O within a three different models: the single a_{1g}-band model with nearest-neighbor hoppings, the realistic three-band t_{2g}-model with, and without e'_g pockets present at the Fermi surface. We show that the magnetic response in the normal state is dominated by the incommensurate antiferromagnetic spin density wave fluctuations at large momenta in agreement with experimental temperature dependence of the spin-lattice relaxation rate. Also, we demonstrate that the presence or the absence of the e'_g-pockets at the Fermi surface does not affect significantly this conclusion. In the superconducting state our results for d_{x^2-y^2}- or d_{xy}-wave symmetries of the superconducting order parameter are consistent with experimental data and exclude nodeless $d_{x^2-y^2} + id_{xy}$-wave symmetry. We further point out that the spin-resonance peak proposed earlier is improbable for the realistic band structure of Na_xCoO_2$\cdot y$H_2O. Moreover, even if present the resonance peak is confined to the antiferromagnetic wave vector and disappears away from it.Comment: Published version, PACS: 74.70.-b; 75.40.Gb; 74.20.Rp; 74.25.J

Particle Propagator of Spin Calogero-Sutherland Model

Explicit-exact expressions for the particle propagator of the spin 1/2 Calogero-Sutherland model are derived for the system of a finite number of particles and for that in the thermodynamic limit. Derivation of the expression in the thermodynamic limit is also presented in detail. Combining this result with the hole propagator obtained in earlier studies, we calculate the spectral function of the single particle Green's function in the full range of the energy and momentum space. The resultant spectral function exhibits power-law singularity characteristic to correlated particle systems in one dimension.Comment: 43 pages, 6 figure

On spectrum of a Schroedinger operator with a fast oscillating compactly supported potential

We study the phenomenon of an eigenvalue emerging from essential spectrum of a Schroedinger operator perturbed by a fast oscillating compactly supported potential. We prove the sufficient conditions for the existence and absence of such eigenvalue. If exists, we obtain the leading term of its asymptotics expansion.Comment: The article is originally written in Russian. The translation in English is made by D. Boriso