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Showing 1 to 20 of 33 for “"Cooper pairs"”.
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Growth and characterisation of Niobium/Gadolinium superconductor-ferromagnet nanocomposites
… which results in the formation of the so-called Cooper pairs, is usually smaller that the exchange (Zeeman) interaction between electrons which tend to align the electron spins. However, non-zero total momentum Cooper pairs can be accomplished even in the presence of an exchange field as …
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Numerical methods of characterizing symmetry protected topological states in one dimension
… is a condensation of four electrons instead of cooper-pairs. While there is a nonzero teleportation for cooper-pairs, the teleportation of one electron is suppressed. The inversion symmetry restricts the edge modes of the system to be cooper-pairs other than two uncorrelated electrons. It is …
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Spin-triplet proximity effects in magnetically controlled heterostructures with s-wave superconductors
… the rapid depairing of conventional spin-singlet Cooper pairs in the presence of a magnetic exchange field. Over the last decade-and-half, experimental evidence has emerged for the generation of spin-triplet Cooper pairs, which have parallel aligned spins, and are therefore compatible with …
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Effects of a single magnetic impurity on superconductivity
… local magnetic field around a vortex breaks up Cooper pairs and suppresses superconduc- tivity locally. Quasiparticle excitations are created and bound in the vortex core area due to repeated Andreev scattering. A magnetic impurity tends to align the spins of the neighboring electrons and break …
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Color superconducting phase of cold dense quark matter
… and strange quarks. The QCD interaction favors Cooper pairs that are antisymmetric in color and in flavor, and a crystalline color superconducting phase can occur which accommodates pairing between flavors with unequal number densities. In the crystalline color superconductor, quarks of …
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Nuclear Magnetic Resonance Studies of the High-Temperature Superconductors in the Normal and Superconducting States
… cores associated with the Doppler shift of the Cooper pairs involved in the screening supercurrent.
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Charge dynamics in superconducting double dots
… of a two level manifold of even charge parity Cooper pair states, and continuous bands corresponding to charge states with single quasiparticles in one or both islands. These devices are fabricated using shadow mask evaporation, and are measured at sub Kelvin temperatures using a dilution …
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Superconducting phase transitions in hybrid superconducting systems with ferromagnets and spin-orbit coupling
… lattice model. In a S/P junction, the singlet Cooper pairs in S cannot mix with the triplet Cooper pairs in P and T_c of both layers remains the same. However, in a S/F/P junction, F converts singlet pairs to triplet pairs, which boosts the P T_c. By rotating the F layer magnetisation, the …
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Spin-mixing and transport through superconducting interlayers in ferromagnetic Josephson junctions
… elements. Supercurrents of spin-aligned triplet Cooper pairs (or ’triplet pairs’) can be generated at magnetically inhomogeneous superconductor/ferromagnet interfaces, and have a longer decay envelope in a ferromagnet than singlet Cooper pairs (or ’singlet pairs’). In this thesis I investigate …
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Superconductor -Insulator Transition in Quasi-One-Dimensional Nanowires
… occurring near the quantum of resistance for Cooper pairs. Wires in the superconducting phase of the SIT are well described by the Langer-Ambegaokar-McCumber-Halperin theory of thermally activated phase slips. No resistance ""tails"" characteristic of quantum phase slips were observed. Wires …
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Superconductor-insulator transition in quasi-one-dimensional nanowires
… occurring near the quantum of resistance for Cooper pairs. Wires in the superconducting phase of the SIT are well described by the Langer-Ambegaokar-McCumber-Halperin theory of thermally activated phase slips. No resistance “tails” characteristic of quantum phase slips were observed. Wires in …
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Communal pairing in Fermi gases with attractive interactions
… spin-balanced fermion gas are known to induce a Cooper pairing instability where the fermion pairs have zero net momentum, leading to BCS superconductivity. Extensions for spin-imbalanced systems include breached superfluids, Fulde–Ferrell–Larkin–Ovchinnikov theory, and pair density wave theory. …
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Investigation of Iron-Based and Topological Superconductors via Point-Contact Spectroscopy
… which are predicted to exhibit unconventional Cooper pairing mechanisms. Point-contact spectra of the iron pnictide BaFe_{1-x}$Pt$_x$As$_2$ are consistent with a two-gap isotropic s-wave model. This conclusion is supported by previously published results from thermal conductivity, …
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Determing the Properties of Dense Matter: Superconductivity, Bulk Viscosity, and Light Reflection in Compact Stars
… star cores. We derive an effective theory of Cooper pair quasiparticles from a microscopic theory of nucleons, and calculate the coupling strengths between quasiparticles. We then calculate the structure of magnetic flux tubes, taking into consideration interactions between neutron and proton …
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SPIN AND CHARGE TRANSPORT IN 2D MATERIALS AND VAN DER WAALS HETEROSTRUCTURES
… of spin supercurrent carried by spin-triplet Cooper pairs in NbSe2. Last but not least, the existence of spin supercurrent is further supported by non-local spin valve measurement. A clear spin signal of magnitude up to 4 Ω was observed. Spin lifetime and diffusion length were extracted from …
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High-temperature superfluidity in an ultracold Fermi gas
… condensate (BEC) of molecules and a Bardeen-Cooper-Schrieffer superfluid of long-range Cooper pairs was studied. Condensates of fermion pairs were detected in a regime where pairing is purely a many-body effect, the pairs being stabilized by the presence of the surrounding particles. …
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Elementary excitations in heavy-fermion superconductors
… superconductors, under the hypothesis that the Cooper pairs are in a relative p-wave or d-wave. First, all p-wave and d-wave states are classified in the presence of strong spin-orbit coupling and crystal fields, which are important effects in heavy-fermions. It is found that p-wave states …
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Numerical study of p-wave superconductivity in Sr2RuO4
… explanation for this is that, instead of the Cooper pairs existing in a spin-singlet state as in most conventional superconductors, the pairs form in an l = 1, or p-wave, angular momentum state. The additional spin degree of freedom offered by this angular momentum state allows the formation …
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Visualizing Cooper Pair Formation on the Atomic Scale in High Temperature Superconductors
… hotly debated issue is the temperature at which Cooper pairs first form. Do pairs form at the critical temperature Tc or do they form at higher temperatures lacking phase rigidity? To answer the question, we have developed new techniques, based on scanning tunneling microscopy, to visualize the …
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Tunneling in Degenerate Atomic Gases
… be used to investigate the coherence of the Cooper pairs. In Chapter 8 we imagine an internal Josephson experiment which uses a pair of lasers to drive transitions between two superfluids. Finally, in Chapter 9 we examine the properties of vortices formed in trapped Cooper-paired fermionic …
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