We study the spectral shape and the magnetic field induced polarization of hot-electron photoluminescence from the diluted magnetic semiconductor Ga,Mn As. It is demonstrated that the holes occupy predominantly the impurity band and not the valence band as required for the Rudermann-Kittel-Kasuya-Yosida-type exchange interaction. We show that the ground state of the impurity band is split by un...

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 unconventional superconductors and our goal is to provide a unified framework for their description. The non-magnetic impurity resonances in unconventional superconduc...

We study how the formation of the Kondo compensation cloud influences the dynamical properties of a magnetic impurity that tunnels between two positions in a metal. The Kondo effect dynamically generates a strong tunneling impurity-conduction electron coupling, changes the temperature dependence of the tunneling rate, and may ultimately result in the destruction of the coherent motion of the pa...

A microscopic expression of the residual electrical resistivity tensor is derived in linear response theory for Rashba electrons scattering at a magnetic impurity with cylindrical or noncylindrical potential. The behavior of the longitudinal and transversal residual resistivity is obtained analytically and computed for an Fe impurity at the Au(111) surface. We studied the evolution of the resis...

We review the progress of nonmagnetic impurity doping studies on Fe-based superconductors. On the theoretical side, two highly promising candidates for the pairing symmetry order parameter, i.e. the multi-gap s++ and s± wave models, have been proposed but continuously debated. The debate arises because of the complex gap structure and exceptional magnetic and metallic behaviors of Fe-based supe...

Using an asymptotic solution of the M -impurity thermodynamics of a dilute s-d system, the impurity energy and impurity heat capacity ∆C(T ) are derived for dilute magnetic alloys with spin 1/2 and spin 3/2 impurities. The parameters which enter ∆C are adjusted to fit experimental data on impurity heat capacity of CuCr and (La1−xCex) Al2. Agreement is satisfactory for CuCr, at temperatures belo...

– A generalized Anderson model for a magnetic impurity in an interacting onedimensional electron gas is studied via a mapping onto a classical Coulomb gas. For weak potential scattering, the local-moment parameter regime expands as repulsive bulk interactions become stronger, but the Kondo scale for the quenching of the impurity moment varies nonmonotonically. There also exist two regimes domin...

Understanding impurity and bulk plasma transport in the scrape-off layer (SOL) of tokamak plasmas is critical for the design of future reactors. The development of a system on Alcator C-Mod for inferring impurity transport behaviour parallel and perpendicular to local magnetic field lines from impurity emission patterns (“plumes”) generated by local gas injection will be presented. Gas is injec...

Low-lying excited states of the spin-1 antiferromagnetic Heisenberg chain with an impurity bond are investigated in terms of domain-wall excitations by means of analytical methods as well as a method of numerical diagonalization. It is shown that 1) the impurity bond brings about a massive triplet mode in the Haldane gap, 2) the triplet state comprises three of the four ground states of an open...

The role of various types of defects in establishing the magnetic properties of the C60-based polymers and the single-wall carbon nanotubes is investigated. Comparing the role of carbon vacancies, and that of substitutional impurity atoms X X=N, B, O, Si, P, and S in establishing a magnetic ground state it is found that the impurity X atoms promote the spin density delocalization, whereas its l...