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Showing 1 to 20 of 26 for “"magnetic impurities"”.
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Electromagnetic penetration depth in superconducting alloys containing magnetic impurities
Measurements of the attenuation of an axial magnetic field by cylindrical, thin, superconducting films were made by using a SQUID-based magnetometer. The sample films were between 40 and 85 A thick. They were composed of indium and of indium containing a small amount of gadolinium. Each film was …
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Upper critical magnetic field of superconducting films with magnetic impurities
We have measured the upper critical magnetic field, H(T), of c2 In-Mn and Pb-Mn alloy films. Hc2 was determined from the resistance of the films. The results were compared with the theory of Fulde and MakL This theory assumes that the electron-phonon coupling is weak, and that the interaction …
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Specific heat of superconducting films of indium and of indium alloyed with magnetic impurities
… the first (investigation of this sort where 3-d magnetic impurities have been studied in a simple metal superconductor. Magnetic impurities depress the superconducting transition temperature T , and predictions based on the Shiba theory for classical spins in c superconductors indicate that …
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Composition dependence of superconductivity in YBa₂(Cu<sub>1-x</sub>A<sub>x</sub>)₃O<sub>6+δ</sub> system with A = Zn, Ni
… discuss our results in terms of pair breaking by magnetic impurities and in terms of the Resonance Valence Bond model proposed by Anderson.
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Quantum spins in semiconductor nanostructures: Hyperfine interactions and optical control
… insulators: The role of time-reversal breaking magnetic impurities in topological materials and how spinful impurities enable backscattering mechanisms by lifting the topological protection of edge modes. I will present a model that allows for an analytical study of the effects of magnetic …
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Electronic thermal conductivity of superconducting lead-manganese, indium-manganese, and indium-chromium alloy films
… on Shiba's theory of superconductors containing magnetic impurities. For Pb-Mn, the value of £ (the normalized position in the energy gap of the excited state assoociated with a single impurity) which was used earlier to explain tunneling measurements, is 0.55; this value is consistent with our …
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The Kondo effect in a single-electron transistor
The Kondo effect, which occurs when a metal with magnetic impurities is cooled to low temperatures, has been a focus of research in solid-state physics for several decades. I have designed, fabricated, and measured a system which behaves as a single "artificial" impurity in a metal, displaying the …
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Ab initio Beschreibung der elektronischen Struktur und der Transporteigenschaften von metallischen Nanodrähten
… The influence of substitutional transition metal impurities on the electronic structure and the conductance of the 2x2 Cu wire is studied. A spin-dependent discussion is given for magnetic impurities.
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Probe of Coherent and Quantum States in Narrow-Gap Based Semiconductors in the Presence of Strong Spin-Orbit Coupling
… properties of the newest member of III-V ferromagnetic structures, InMnSb, as well as InSb films and InSb/AlInSb quantum wells. The emphasis was on dynamical aspects such as charge and spin dynamics in order to address several important issues of the spin-related phenomena. The objectives in …
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Theoretical study of Kondo effect and related transport properties in topological insulator systems
… For the first topic, we investigate the role of magnetic impurities in the transport properties of a three dimensional topological insulator's surface states. First, we combine the second-order perturbation theory and the Boltzmann transport equation to calculate the magnetically induced …
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Transitional impurities in liquid copper
… the solutes Crt Mn, Fe, and Co possess localized magnetic moments in these alloys. The impurity moments were calculated from the susceptibility and found to change little on melting. The Cu63 Knight shift in liquid copper is found to be decreased by dissolved transition impurities with the maximum …
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Scanning tunneling microscopy and spectroscopy of topological materials with broken symmetry
… electronic properties of topological materials. Magnetic doping was then added to induce ferromagnetism, which creates an energy gap in the surface states of (Bi1-xSbx)2Te3. Tunneling conductance spectroscopy was used to examine the correlation between the density of magnetic impurities and the …
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Field theoretical methods for strongly correlated electron systems
… slave-fermion technique to study the physics of magnetic impurities both in Quantum Antiferromagnets (in a flux phase) and in d-wave superconductors. This is a system consisting of a magnetic impurity coupled to either the low lying excitations of a flux phase, or to the normal quasi-particles …
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Josephson Interferometry Measurements in High-T(c) Grain Boundary Junctions
… is predicted to occur in the bulk film near magnetic impurities. Calculations demonstrate that the temperature and magnetic field dependence of the critical current of 45° asymmetric grain boundary Josephson junctions are extremely sensitive to the onset of a complex order parameter. We …
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Josephson Interferometry Measurements in High-Tc Grain Boundary Junctions
… is predicted to occur in the bulk film near magnetic impurities. Calculations demonstrate that the temperature and magnetic field dependence of the critical current of 45° asymmetric grain boundary Josephson junctions are extremely sensitive to the onset of a complex order parameter. We have …
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Effects of doping on the electronic properties of niobium triselenide
… Wave (CDW) material NbSe3 are reported. The magnetic studies show that both magnetic(V) and nonmagnetic(Ta) impurities may be introduced into NbSe3; a sensitive electron microscopy technique for measuring the impurity concentration is described. Magnetic impurities form delocalized states …
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Solid State Nuclear Magnetic Resonance of Quadrupolar Nuclei (Nmr)
Solid State Nuclear Magnetic Resonance has been used to study a variety of systems of geologic and chemical interest including feldspars, phyllosilicates, zeolites and aluminas. High magnetic field strengths (8.5 T) and Magic Angle Sample Spinning (MASS) yield high resolution spectra for …
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Time-Resolved Studies of Magnetic and Non-Magnetic Narrow-Gap Semiconductors
… In this thesis, time-resolved studies of magnetic and non-magnetic NGS using ultrafast-laser spectroscopy techniques such as pump-probe spectroscopy and magneto-optical Kerr/Faraday effect, are reported. Our samples include: InSb-based quantum wells with different confinement potentials; …
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A search for superconductivity in conjugated polymers
… in a conjugated polymer with implanted magnetic atoms. To carry out this investigation we have performed a modified worldline quantum Monte Carlo (QMC) algorithm concentrating on the polymer cis-polyacetylene at finite temperatures. The Hamiltonian used is that of the extended …
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Mapping the magnetization density near magnetic atoms in copper: Nuclear magnetic resonance studies of CuMn and CuCr
"Using nuclear magnetic resonance, we have measured the magnetization density at the nuclear sites of several copper near neighbor shells surrounding the impurities manganese and chromium in the dilute alloys CuMn and CuCr. The resonances of these neighbor shells appear as weak ""satellite"" …
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