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A simple two-band model with interband scattering of intraband pairs is applied to MgB$_2$ superconductivity. An adjustable parameters set is chosen. The calculated $T_c$ vs doping, isotope exponent and the heat capacity jump are in…

Superconductivity · Physics 2016-08-31 N. Kristoffel , T. Örd

Isotope effects in a multiband superconductor with a leading interband pairing channel are investigated. A relatively small electron-phonon contribution into the pair-transfer interaction can cause effects of observed magnitude. A multiband…

Superconductivity · Physics 2007-05-23 N. Kristoffel , P. Rubin

The BCS electron-phonon mechanism and the unconventional 'hole mechanism' have been proposed as explanations for the high temperature superconductivity observed in $MgB_2$. It is proposed that a critical test of which theory is correct is…

Superconductivity · Physics 2009-11-07 J. E. Hirsch , F. Marsiglio

We investigate the influence of electron-phonon coupling on the superexchange interaction of magnetic insulators. Both the Holstein-Hubbard model where the phonons couple to the electron density, as well as an extended Su, Schrieffer,…

Condensed Matter · Physics 2009-10-28 W. Stephan , M. Capone , M. Grilli , C. Castellani

State-of-the-art model Hamiltonians, like Fr\"ohlich's, or density functional theory approaches to electron-phonon interaction suffer from a severe overscreening error. This is due to the incorrect treatment of the screening of the ionic…

Materials Science · Physics 2023-11-17 Fulvio Paleari , Andrea Marini

The electronic structure and thermoelectric properties of are studied by the first principles and the semiclassical BoltzTrap theory.

Materials Science · Physics 2017-09-13 Gui Yang , jueming Yang , Yuli Yan , Yuanxu Wang

Effect of tetragonal distortion on the electronic structure, dynamical properties and superconductivity in Mo$_3$Sb$_7$ is analyzed using first principles electronic structure and phonon calculations. Rigid muffin tin approximation (RMTA)…

Superconductivity · Physics 2014-05-27 Bartlomiej Wiendlocha , Malgorzata Sternik

Li2Pd3B is known to be superconducting, while the isotypical Li2Pt3B compound is not. Electronic structures of Li2Pd3B and Li2Pt3B have been calculated in order to obtain an insight into this surprising difference, through an analysis of…

Superconductivity · Physics 2009-11-11 Sharat Chandra , S. Mathi Jaya , M. C. Valsakumar

The phonon density-of-states of transition metal diborides TMB2 with TM = Ti, V, Ta, Nb and Y has been measured using the technique of inelastic neutron scattering. The experimental data are compared with ab initio density functional…

Superconductivity · Physics 2009-11-10 R. Heid , B. Renker , H. Schober , P. Adelmann , D. Ernst , K. -P. Bohnen

We have studied the changes in the electronic structure and the superconducting transition temperature T_c of Mg(B_{1-x}C_{x})_{2} alloys as a function of x with 0\leq x\leq 0.3. Our density-functional-based approach uses coherent-potential…

Superconductivity · Physics 2009-11-10 Prabhakar P. Singh

In the present work we calculate the tunneling density of states (DOS) of MgB% $_{2}$ for different tunneling directions by directly solving the two-band Eliashberg equations (EE) in the real-axis formulation. This procedure reveals the…

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

Pseudogap phase in superconductors continues to be an outstanding puzzle that differentiates unconventional superconductors from the conventional ones (BCS-superconductors). Employing high resolution photoemission spectroscopy on a highly…

The title compound is investigated by specific heat measurements in the normal and superconducting state supplemented by upper critical field transport, susceptibility and magnetization measurements. From a detailed analysis including also…

The physics of ferromagnetic doped manganites, such as \chem{La_{1-x}Ca_xMnO_3} with $x\approx0.2$--0.4, is reviewed. The concept of double exchange is discussed within the general framework of itinerant electron magnetism. The new feature…

Strongly Correlated Electrons · Physics 2015-06-24 D. M. Edwards

An overview on recent efforts in point-contact (PC) spectroscopy of title superconductors is given. Distinct phonon features and crystalline-electric-field effects are observed in PC spectra of HoNi2B2C. Results of study of superconducting…

Density functional calculations are used to investigate the effects of partial substitutional alloying of the B site in MgB2 with C and Be alone and combined with alloying of the Mg site with Cu. The effect of such substitutions on the…

Superconductivity · Physics 2009-11-07 M. J. Mehl , D. A. Papaconstantopoulos , D. J. Singh

I present the results of first principles calculations of the phonon dispersions and electron-phonon coupling for BaTi$_2$Sb$_2$O. The phonon dispersions show a weak lattice instability near the zone corners that leads to a charge-density…

Superconductivity · Physics 2013-02-18 Alaska Subedi

The electronic structure, stability, electron phonon coupling and superconductivity of the non-oxide perovskite MgCNi$_3$ are studied using density functional calculations. The band structure is dominated by a Ni $d$ derived density of…

Superconductivity · Physics 2009-11-07 D. J. Singh , I. I. Mazin

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

Recent theoretical results on magnetotransport of electrons in a 2D system in the range of moderately strong transverse magnetic fields are reviewed. The phenomena discussed include: quasiclassical memory effects in systems with various…

Disordered Systems and Neural Networks · Physics 2008-02-01 I. A. Dmitriev , F. Evers , I. V. Gornyi , A. D. Mirlin , D. G. Polyakov , P. Wölfle