Related papers: Impurity spin dynamics in 2D antiferromagnets and …
The effects of nonmagnetic impurity on the spin excitation spectra in a $d_{x^2-y^2}$-wave superconductor are examined, using the self-consistent $t$-matrix approximation. It is shown that the impurity self-energy acts to shift the position…
A theory of magnetic impurities in a 2D electron gas quantized by a strong magnetic field is formulated in terms of Friedel-Anderson theory of resonance impurity scattering. It is shown that this scattering results in an appearance of bound…
We consider a magnetic impurity in a spin liquid state of a magnetic system which is close to the quantum phase transition to the magnetically ordered state. There is similarity between this problem and the Kondo problem. We derive the…
The spin texture surrounding a non-magnetic impurity in a quantum antiferromagnet is a sensitive probe of the novel physics of a class of quantum phase transitions between a Neel ordered phase and a valence bond solid phase in square…
The spin-fluctuation based pairing mechanism has proven successful in explaining the pairing symmetries due to Fermi surface nesting of both cuprates and iron-based materials. In this work, we study signatures of a spin-fluctuation mediated…
The effects of spin-1 impurities introduced in dimerized antiferromagnetic spin chains are studied using Lanczos diagonalization and quantum Monte Carlo simulations. Firstly, the magnitude of the interaction between a Ni-ion replacing a…
A formalism is developed to treat magnetic impurities in a Mott-Hubbard antiferromagnetic insulator within a representation involving multiple orbitals per site. Impurity scattering of magnons is found to be strong when the number of…
We present a new formulation of the theory of an arbitrary quantum impurity in an antiferromagnet, using the O(3) non-linear sigma model. We obtain the low temperature expansion for the impurity spin susceptibilities of antiferromagnets…
Spin relaxation in the impurity band of a 2D semiconductor with spin-split spectrum in the external magnetic field is considered. Several mechanisms of spin relaxation are shown to be relevant. The first one is attributed to phonon-assisted…
By using a model Hamiltonian with d-wave superconductivity and competing antiferromagnetic (AF) orders, the local staggered magnetization distribution due to nonmagnetic impurities in cuprate superconductors is investigated. From this, the…
We demonstrate how potential impurities are a very powerful tool for determining the pairing symmetry in graphene proximity-coupled to a spin-singlet superconductor. All d-wave states are characterized by subgap resonances, with spatial…
We present results of tight-binding spin-dynamics simulations of individual and pairs of substitutional Mn impurities in GaAs. Our approach is based on the mixed quantum-classical scheme for spin dynamics, with coupled equations of motions…
We predict a general local spin-flip transition mechanism caused by magnetic quantum impurities in (partially) polarized phases of quantum magnets in the absence of conservation laws. This transition arises when a magnon bound state crosses…
The $S=1/2$ antiferromagnetic Heisenberg spin chain compound Sr$_2$CuO$_3$ doped with $1 \%$ and $2 \%$ of Ni impurities has been studied by means of $^{63}$Cu nuclear magnetic resonance. A strong decrease of the spin-lattice relaxation…
Qualitative differences in the spectrum of a superconductor near magnetic impurity pairs with moments aligned parallel and antiparallel are derived. A proposal is made for a new, nonmagnetic scanning tunneling spectroscopy of magnetic…
Thermodynamic properties are presented for four magnetic impurity models describing delocalized fermions scattering from a localized orbital at an energy-dependent rate $\Gamma(\epsilon)$ which vanishes precisely at the Fermi level,…
We consider electronic spectra of graphene nanotubes and their perturbation by impurity atoms absorbed at different positions on nanotube surfaces, within the framework of Anderson hybrid model. A special attention is given to the cases…
Impurities, which are inherently present in any real material, may play an important role in the magnetism of frustrated spin systems with spin-liquid ground states. We address the impurity issue in quantum kagome antiferromagnets by…
We review recent developments in our understanding of how impurities influence the electronic states in the bulk of superconductors. Our focus is on the quasi-localized states in the vicinity of impurity sites in conventional and…
Dynamical properties of an impurity spin coupled symmetrically to sublattices of ordered 2D Heisenberg quantum antiferromagnet (i.e., frustrated impurity spin) are discussed at $T\ge0$ (existence of a small interaction stabilizing the long…