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Related papers: Multiband model for penetration depth in MgB2

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A study of the pressure effect on the magnetic penetration depth $\lambda$ in polycrystalline MgB$_{2}$ was performed by measuring the temperature dependence of the magnetization under an applied pressure of 0.15 and 1.13 GPa. We found that…

Superconductivity · Physics 2009-11-10 D. Di Castro , R. Khasanov , C. Grimaldi , J. Karpinski , S. M. Kazakov , H. Keller

We measure phonon dispersion and linewidth in a single crystal of MgB_2 along the Gamma-A, Gamma-M and A-L directions using inelastic X-Ray scattering. We use Density Functional Theory to compute the effect of both electron-phonon coupling…

Recent experimental data of anisotropic magnetoresistivity measured in MgB2 films have shown an intriguing behaviour: the angular dependence of magnetoresistivity changes dramatically with temperature and disorder. In order to explain such…

Superconductivity · Physics 2007-05-23 I. Pallecchi , M. Monni , C. Ferdeghini , V. Ferrando , M. Putti , C. Tarantini , E. Galleani D'Agliano

We study the effects of C substitutions in MgB_2 within the two-band model in the Eliashberg formulation. We use as input the B-B stretching-mode frequency and the partial densities of states N_{sigma}(EF) and N_{pi}(EF), recently…

Superconductivity · Physics 2009-11-10 G. A. Ummarino , D. Daghero , R. S. Gonnelli , A. H. Moudden

We calculate the tunneling density of states (DOS) of MgB2 for different tunneling directions, by directly solving the real-axis, two-band Eliashberg equations (EE). Then we show that the numeric inversion of the standard single-band EE, if…

Superconductivity · Physics 2009-11-10 D. Daghero , R. S. Gonnelli , G. A. Ummarino , O. V. Dolgov , J. Kortus , A. A. Golubov , S. V. Shulga

We study the low-temperature thermodynamics of a spin-S magnetic impurity coupled to m degenerate bands of interacting electrons in one dimension. By exploiting boundary conformal field theory techniques, we derive exact results for the…

Strongly Correlated Electrons · Physics 2009-10-30 M. Granath , H. Johannesson

Metals with many bands at the Fermi level can have different band dependent gaps in the superconducting state. The absence of translational symmetry at an interface can induce interband scattering and modify the superconducting properties.…

Condensed Matter · Physics 2009-11-07 E. Bascones , F. Guinea

The search of the phonon structure at the above-gap energies was carried out for $d^{2}V/dI^{2}(V)$ spectra of MgB$_{2}$ point contacts with a normal metal. The two-band model is assumed not only for the gap structure in…

Superconductivity · Physics 2009-11-07 I. K. Yanson , V. V. Fisun , N. L. Bobrov , Yu. G. Naidyuk , W. N. Kang , Eun-Mi Choi , Hyun-Jung Kim , Sung-Ik Lee

Choi et al. [Phys. Rev. B 66, 020513 (2002)] recently presented first principles calculations of the electron-phonon coupling and superconductivity in MgB2, emphasizing the importance of anisotropy and anharmonicity. We point out that (1)…

Superconductivity · Physics 2007-05-23 I. I. Mazin , O. K. Andersen , O. Jepsen , A. A. Golubov , O. V. Dolgov , J. Kortus

We have measured the magnetic penetration depth of the recently discovered binary superconductor MgB_2 using muon spin rotation and low field $ac$-susceptibility. From the damping of the muon precession signal we find the penetration depth…

Superconductivity · Physics 2009-11-07 C. Panagopoulos , B. D. Rainford , T. Xiang , C. A. Scott , M. Kambara , I. H. Inoue

The temperature dependence of the London penetration depth ($\lambda$) and coherence length ($\xi$) has been deduced from Hall probe magnetization measurements in high quality MgB$_2$ single crystals in the two main crystallographic…

Superconductivity · Physics 2009-11-10 L. Lyard , P. Szabo , T. Klein , J. Marcus , C. Marcenat , B. W. Kang , K. H. Kim , H. S. Lee , S. I. Lee

We have studied the anisotropy of the London penetration depth, which was obtained from reversible magnetization measurements with the magnetic field both parallel and perpendicular to the c-axis. The anisotropy of the London penetration…

Superconductivity · Physics 2009-11-10 Heon-Jung Kim , Byeongwon Kang , Min-Seok Park , Kyung-Hee Kim , Hyun Sook Lee , Sung-Ik Lee

The study of the anisotropic superconductor MgB2 using a combination of scanning tunneling microscopy and spectroscopy reveals two distinct energy gaps at Delta1=2.3 meV and Delta2=7.1 meV. Different spectral weights of the partial…

Superconductivity · Physics 2009-11-07 M. Iavarone , G. Karapetrov , A. E. Koshelev , W. K. Kwok , G. W. Crabtree , D. G. Hinks

We discuss the effects of anisotropy on superconducting critical temperature and order parameter in a strongly coupled regime. The multiband representation is used as a model for anisotropy. We show that strong coupling effects in multiband…

Superconductivity · Physics 2009-11-13 O. V. Dolgov , A. A. Golubov

Based on a detailed modeling of the Fermi surface topology of MgB2 we calculated the anisotropy of the upper critical field Bc2 within the two gap model. The sigma-band is modeled as a distorted cylinder and the pi-band as a half-torus,…

Superconductivity · Physics 2007-05-23 T. Dahm , S. Graser , N. Schopohl

The magnetic-field-induced variations of the microwave surface resistance have been investigated in a heavily neutron-irradiated MgB2 sample, in which the irradiation has caused the merging of the two gaps into a single value. The…

Superconductivity · Physics 2008-12-19 M. Bonura , A. Agliolo Gallitto , M. Li Vigni , A. Martinelli

The influence of electron-phonon interaction on magnetotransport in two-dimensional electron systems under microwave irradiation is studied theoretically. Apart from the phonon-induced resistance oscillations which exist in the absence of…

Mesoscale and Nanoscale Physics · Physics 2015-05-18 O. E. Raichev

In systems having an anisotropic electronic structure, such as the layered materials graphite, graphene and cuprates, impulsive light excitation can coherently stimulate specific bosonic modes, with exotic consequences for the emergent…

The progress in investigation of two-band superconductor MgB$_2$ by the point-contact spectroscopy (PCS) is given. Results of study of superconducting gap temperature and magnetic field dependence for two-dimensional $\sigma$ and…

Superconductivity · Physics 2007-05-23 I. K. Yanson , Yu. G. Naidyuk

Based on weakly-coupled anisotropic BCS theory, the dependence of energy gap and specific heat on temperature are evaluated for superconductor MgB$_2$, and the results are compared with experimental data.We show that the weak coupling…

Superconductivity · Physics 2007-05-23 Todor M. Mishonov , Valery L. Pokrovsky , Hongduo Wei