Ginsburg-Landau Expansion in a non-Fermi Superconductor

We study the Ginsburg-Landau expansion for the non-Fermi model proposed by Anderson. We analyze the deviations of the main properties of a non-Fermi superconductor from the isotropic s-wave bidimensiona superconductor.Comment: 7 pages, 3 figures, accepted for publication in Physica

Measurement of Quantum Noise in a Carbon Nanotube Quantum Dot in the Kondo Regime

The current emission noise of a carbon nanotube quantum dot in the Kondo regime is measured at frequencies ν of the order or higher than the frequency associated with the Kondo effect kBTK/h, with TK the Kondo temperature. The carbon nanotube is coupled via an on-chip resonant circuit to a quantum noise detector, a superconductor-insulator-superconductor junction. We find for hν≈kBTK a Kondo effect related singularity at a voltage bias eV≈hν, and a strong reduction of this singularity for hν≈3kBTK, in good agreement with theory. Our experiment constitutes a new original tool for the investigation of the nonequilibrium dynamics of many-body phenomena in nanoscale devices

Transport Properties Calculation for a Quasi-Bidimensional System using T-Matrix Approximation

We performed a self-consistent calculation using T-Matrix approximation for a quasi-bidimensional system. We calculated the one particle spectrum function A(k,\omega) in the presence of strong d-wave attractive interaction. The c-axis charge dynamics was studied by considering incoherent interlayer hopping and ab-plane charge dynamics was studied in the coherent limit. It is shown that the c-axis charge dynamics is mainly governed by the scattering from the in plane fluctuations. We also present results for c-axis and ab-plane resistivity and for thermopower coefficient.Comment: 10 pages, 13 figures, accepted for publication in Physica

Mixed state properties of superconducting MgB2 single crystals

We report on measurements of the magnetic moment in superconducting MgB2 single crystals. We find \mu_0H_{c2}^c(0) = 3.2 T, \mu_0H_{c2}^{ab}(0) = 14.5 T, \gamma = 4.6, \mu_0H_c(0) = 0.28 T, and \kappa(T_c) = 4.7. The standard Ginzburg-Landau and London model relations lead to a consistent data set and indicate that MgB2 is a clean limit superconductor of intermediate coupling strength with very pronounced anisotropy effects

Transport Properties Calculation in the Superconducting State for a Quasi-Twodimensional System

We performed a self-consistent calculation of the transport properties of a d-wave superconductor. We used for calculations the T-matrix approximation. The coresponding equations were evaluated numerically directly on the real frequecy axis. We studied the ab-plane charge dynamics in the coherent limit. For the c-axis charge dynamics, we considered both, the coherent and the incoherent limit. We also have calculated the penetration depth in this model.Comment: 7 pages, 6 figures, to appear in Physica

Ginzburg-Landau Expansion in Non-Fermi Liquid Superconductors: Effect of the Mass Renormalization Factor

We reconsider the Ginzburg-Landau expansion for the case of a non-Fermi liquid superconductor. We obtain analytical results for the Ginzburg-Landau functional in the critical region around the superconducting phase transition, T <= T_c, in two special limits of the model, i.e., the spin-charge separation case and the anomalous Fermi liquid case. For both cases, in the presence of a mass renormalization factor, we derived the form and the specific dependence of the coherence length, penetration depth, specific heat jump at the critical point, and the magnetic upper critical field. For both limits the obtained results reduce to the usual BCS results for a two dimensional s-wave superconductor. We compare our results with recent and relevant theoretical work. The results for a d--wave symmetry order parameter do not change qualitatively the results presented in this paper. Only numerical factors appear additionally in our expressions.Comment: accepted for publication in Physical Review

Penetration depth anisotropy in two-band superconductors

The anisotropy of the London penetration depth is evaluated for two-band superconductors with arbitrary inter- and intra-band scattering times. If one of the bands is clean and the other is dirty in the absence of inter-band scattering, the anisotropy is dominated by the Fermi surface of the clean band and is weakly temperature dependent. The inter-band scattering also suppress the temperature dependence of the anisotropy

Combining the in-medium similarity renormalization group with the density matrix renormalization group: Shell structure and information entropy

We propose a novel many-body framework combining the density matrix renormalization group (DMRG) with the valence-space (VS) formulation of the in-medium similarity renormalization group. This hybrid scheme admits for favorable computational scaling in large-space calculations compared to direct diagonalization. The capacity of the VS-DMRG approach is highlighted in ab initio calculations of neutron-rich nickel isotopes based on chiral two- and three-nucleon interactions, and allows us to perform converged ab initio computations of ground and excited state energies. We also study orbital entanglement in the VS-DMRG, and investigate nuclear correlation effects in oxygen, neon, and magnesium isotopes. The explored entanglement measures reveal nuclear shell closures as well as pairing correlations.ISSN:0370-2693ISSN:0031-9163ISSN:1873-244

Replication Data for: 'Imaging the Electronic Wigner Crystal in One Dimension'

This data set contains all data presented in the paper 'Imaging the Electronic Wigner Crystal in One Dimension

Point-Contact Spectroscopy in Mn-Doped MgB2 Single Crystals: Effects of Magnetic Impurities in a Two-Band Superconductor

We performed point-contact spectroscopy (PCS) measurements in Mg1−xMnxB2 single crystals, with x ≤ 0.015 and bulk Tc down to 13.3 K. The gaps σ and π were obtained by fitting the conductance curves of the point contacts with the two-band Blonder-Tinkham- Klapwijk (BTK) model. Both σ and π decrease with the critical temperature of the junctions TAc , but remain clearly distinct down to the lowest critical temperature (TAc∼=9 K). Once analyzed within the Eliashberg theory, the gap trends as a function of TAc can be explained by a doping-induced increase in the pair-breaking scattering within the σ band, with smaller contributions from the π-π or the σ-π channel