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We have reexamined the problem of disorder in two-band superconductors, and shown within the framework of the T-matrix approximation, that the suppression of T_c can be described by a single parameter depending on the intraband and…

Superconductivity · Physics 2015-03-19 D. V. Efremov , M. M. Korshunov , O. V. Dolgov , A. A. Golubov , P. J. Hirschfeld

We prepared MgB$_{2-x}$Be$_{x}$ ($x=0$, 0.2, 0.3, 0.4, and 0.6) samples where B is substituted with Be. MgB$_{2}$ structure is maintained up to $x=0.6$. In-plane and inter-plane lattice constants were found to decrease and increase,…

Superconductivity · Physics 2009-11-07 J. S. Ahn , Y. -J. Kim , M. -S. Kim , S. -I. Lee , E. J. Choi

The single-site two-electron exchange amplitude J_sd between the Cu 4s and Cu 3d_{x^2-y^2} states is found to be the pairing mechanism of high-T_c overdoped cuprates. The noninteracting part of the Hamiltonian spans the copper Cu 4s, Cu…

Superconductivity · Physics 2007-05-23 T. M. Mishonov , J. O. Indekeu , E. S. Penev

We report a significant enhancement of superconducting transition temperature ($\textit{T}_\textrm{c}$) of transition metal dichalcogenide (TMD) superconductor $\textrm{NbTe}_2$ from 0.56 K to 2.8 K. Detailed x-ray structure analysis…

We study nonmagnetic impurity effects in MgB$_{2}$ using the quasiclassical equations of superconductivity for a weak-coupling two-band model. Parameters in the model are fixed so as to reproduce experiments on MgB$_{2}$ as closely as…

Superconductivity · Physics 2009-11-10 Koichi Watanabe , Takafumi Kita

Point contact junctions made from two pieces of MgB2 can be adjusted to exhibit either superconductor-insulator-superconductor (SIS) or superconductor-normal metal-superconductor (SNS) current-voltage characteristics. The SIS…

Superconductivity · Physics 2009-11-07 Y. Zhang , D. Kinion , J. Chen , D. G. Hinks , G. W. Crabtree , John Clarke

Emerging in the 1950s, the multiband superconductivity has been considered for a long time as an approximate model in the form of a generalization of the BCS theory to the case of two bands for a more accurate quantitative description of…

Superconductivity · Physics 2017-12-05 Y. Yerin , A. N. Omelyanchouk

A simple model of cuprate superconductivity with an electron spectrum prepared by doping is developed. The pair-transfer interaction couples the itinerant band with two components ("hot'' and "cold'') of the defect subsystem. There are…

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

The proximity effect between a superconductor and a highly diffusive two-dimensional metal was revealed in a Scanning Tunneling Spectroscopy experiment. The in-situ elaborated samples consisted of superconducting single crystalline Pb…

In the usual perception, surface superconductivity is associated with the surface nucleation of a superconducting condensate above the upper critical field in type-II superconductors or with a rearrangement of phonon properties and the…

Superconductivity · Physics 2023-01-31 Yunfei Bai , Yajiang Chen , M. D. Croitoru , A. A. Shanenko , Xiaobing Luo , Yunbo Zhang

We report $^{11}$B-NMR study on Al-doped MgB$_2$ that addresses a possible mechanism for a high superconducting (SC) transition temperature ($T_c$) of $\sim 40$ K in recently discovered MgB$_2$. The result of nuclear spin lattice relaxation…

Superconductivity · Physics 2009-11-07 H. Kotegawa , K. Ishida , Y. Kitaoka , T. Muranaka , N. Nakagawa , H. Takagiwa , J. Akimitsu

The band structure and the Fermi surface of hexagonal diborides ZrB2, VB2, NbB2, TaB2 have been studied by the self-consistent full-potential LMTO method and compared with those for the isostructural superconductor MgB2. Factors responsible…

Superconductivity · Physics 2007-05-23 I. R. Shein , A. L. Ivanovskii

AlN-GaN heterostructures are central to high-power and high-frequency electronics, including RF devices, power converters, and AI accelerators. An intermediate Al1-xGaxN (AlGaN) layer is often present, either unintentionally during growth…

Materials Science · Physics 2026-01-21 Khalid Zobaid Adnan , Hao Zhou , Tianli Feng

We have studied the electron-phonon and superconducting properties of the Mg{1-x}AlxB2 and MgB{2(1-y)}C{2y} alloys within the framework of density functional theory using the self-consistent virtual-crystal approximation. For both alloys,…

Superconductivity · Physics 2010-12-16 O. De la Peña-Seaman , R. de Coss , R. Heid , K. -P. Bohnen

We solve the coupled gap equations for the $\sigma$- and $\pi$-bands of MgB$_2$ in the vortex state and calculate the resulting field dependencies of the specific heat coefficient $\gamma$ and the thermal conductivity $\kappa $. The crucial…

Superconductivity · Physics 2009-11-10 L. Tewordt , D. Fay

Chiral superconductors support chiral edge modes and potentially spontaneous edge currents at their boundaries. Motivated by the putative multiband chiral p-wave superconductor Sr$_2$RuO$_4$, we study the influence of the interference…

Superconductivity · Physics 2017-12-07 Jia-Long Zhang , Wen Huang , Manfred Sigrist , Dao-Xin Yao

Through a comprehensive free energy analysis, we demonstrate that finite temperature can simultaneously weaken superconductivity and mitigate spin polarization induced depairing, leading to potential non-monotonic temperature-dependent…

Superconductivity · Physics 2025-11-25 Xusheng Wang , Lianyi He , Shuai-hua Ji

Interplay of superconductivity and magnetism in a composite prepared of the ferromagnetic half-metallic La_0.67Sr_0.33MnO (LSMO) nanoparticles and the conventional s-wave superconductor MgB_2 has been studied. A few principal effects have…

Superconductivity · Physics 2013-05-30 V. N. Krivoruchko , V. Yu. Tarenkov

There is a tacit assumption that multiband superconductors are essentially the same as multigap superconductors. More precisely, it is usually assumed that the number of excitation gaps in the single-particle energy spectrum of a uniform…

Multiband superconductivity with dominant two-gap features are recently proposed to challenge the earlier accepted nodal $d$-wave pairing in the first unconventional superconductor CeCu$_{2}$Si$_{2}$. Here we obtain multiband Fermi-surface…

Superconductivity · Physics 2018-03-16 Dongdong Wang , Bin Liu , Min Liu , Yi-feng Yang , Shiping Feng