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Heat-capacity measurements of a 39 microgramm MgB_2 single crystal in fields up to 14 T and below 3 K allow the determination of the low-temperature linear term of the specific heat, its field dependence and its anisotropy. Our results are…

Superconductivity · Physics 2009-11-07 F. Bouquet , Y. Wang , I. Sheikin , T. Plackowski , A. Junod , S. Lee , S. Tajima

Superconductivity has been first observed in TlNi$_2$Se$_2$ at T$_C$=3.7 K and appears to involve heavy electrons with an effective mass $m^*$=14$\sim$20 $m_b$, as inferred from the normal state electronic specific heat and the upper…

Superconductivity · Physics 2013-11-20 Hangdong Wang , Chiheng Dong , Qianhui Mao , Rajwali Khan , Xi Zhou , Zhenxia Li , Bin Chen , Jinhu Yang , Qiping Su , Minghu Fang

The Ginzburg-Landau coefficients, and the jump of the specific heat are calculated for a disordered two-band superconductor. We start with the analysis of a more general case arbitrary anisotropy. While the specific heat discontinuity at…

Superconductivity · Physics 2009-11-07 Todor M. Mishonov , Evgeni S. Penev , Joseph O. Indekeu , Valery L. Pokrovsky

We consider a model for superconductivity in a two-band superconductor, having an anisotropic electronic structure made of two partially overlapping bands with a first hole-like and a second electron-like fermi surface. In this pairing…

Superconductivity · Physics 2010-12-16 Alex A. Schmidt , Jose J. Rodríguez-Núñez , Antonio Bianconi , Andrea Perali

To resolve the discrepancies of the superconducting order parameter in quasi-two-dimensional NbSe_2, comprehensive specific-heat measurements have been carried out. By analyzing both the zero-field and mixed-state data with magnetic fields…

Superconductivity · Physics 2009-11-13 C. L. Huang , J. -Y. Lin , Y. T. Chang , C. P. Sun , H. Y. Shen , C. C. Chou , H. Berger , T. K. Lee , H. D. Yang

The two-gap model for superconductivity in MgB2 predicts that interband impurity scattering should be pair breaking, reducing the critical temperature. This is perhaps the only prediction of the model that has not been confirmed…

Superconductivity · Physics 2009-11-10 Steven C. Erwin , I. I. Mazin

This paper reports specific-heat measurements on superconducting MgB2 in magnetic fields to 9 T. In zero magnetic field the data can be fitted to a two-gap model, which is a generalization of a semi-empirical model for strong-coupled,…

Superconductivity · Physics 2007-05-23 R. A. Fisher , F. Bouquet , N. E. Phillips , D. G. Hinks , J. D. Jorgensen

The specific heat of two polycrystalline samples of MgB_2 is presented and analyzed (2 - 300 K, 0 - 16 T), together with magnetic properties. The main characteristics are a low density of states at the Fermi level, high phonon frequencies,…

Superconductivity · Physics 2007-05-23 Alain Junod , Yuxing Wang , Frederic Bouquet , Pierre Toulemonde

The superconducting state of Mg$^{10}$B$_{2}$ is investigated by specific heat measurements in detail. The specific heat in the normal state is analyzed using a recently developed computer code. This allows for an extraction of the…

Superconductivity · Physics 2007-05-23 A. Wälte , S. -L. Drechsler , G. Fuchs , K. -H. Müller , K. Nenkov , D. Hinz , L. Schultz

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

We show that the specific heat of the superconductor MgB_2 (MgB2) in zero field, for which significant non-BCS features have been reported, can be fitted, essentially within experimental error, over the entire range of temperature to T_c by…

Superconductivity · Physics 2009-11-07 F. Bouquet , Y. Wang , R. A. Fisher , D. G. Hinks , J. D. Jorgensen , A. Junod , N. E. Phillips

This paper discusses the synthesis, characterization, and comprehensive study of Ba-122 single crystals with various substitutions and various $T_c$. The paper uses five complementary techniques to obtain a self-consistent set of data on…

We explore the temperature effects in the superconducting phases of a hybridized two-band system. We show that for zero hybridization between the bands, there are two different critical temperatures. However, for any finite hybridization…

Superconductivity · Physics 2018-05-23 Heron Caldas , A. Celes , David Nozadze

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 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

We report on the determination of the electronic heat capacity of a slightly overdoped (x = 0.075) Ba(Fe1-xCox)2As2 single crystal with a Tc of 21.4 K. Our analysis of the temperature dependence of the superconducting-state specific heat…

Superconductivity · Physics 2015-05-14 F. Hardy , T. Wolf , R. A. Fisher , R. Eder , P. Schweiss , P. Adelmann , H. v. Loehneysen , C. Meingast

This article is a review o over theory of superconductivity, which is constructed for systems with two overlapping energy bands at the Fermi surface and with arbitrary charge carrier density.There is taken into account all possible kinds of…

Superconductivity · Physics 2007-05-23 M. E. Palistrant

The structure of the superconducting gap provides important clues on the symmetry of the order parameter and the pairing mechanism. The presence of nodes in the gap function imposed by symmetry implies an unconventional order parameter,…

Superconductivity · Physics 2015-05-13 H Shakeripour , C Petrovic , Louis Taillefer

Superconducting order parameter and its symmetry are important parameters towards deciphering the pairing mechanism in newly discovered superconducting systems. We report a study on penetration depth measurement on Nb2PdS5 that has recently…

Superconductivity · Physics 2016-04-20 Shruti , R. Goyal , V. P. S Awana , S. Patnaik

The heat capacity of a 2H-NbS2 single crystal has been measured by a highly sensitive ac technique down to 0.6 K and in magnetic fields up to 14 T. At very low temperatures data show excitations over an energy gap (2DS/kBTc \approx 2.1)…

Superconductivity · Physics 2015-05-20 J. Kacmarcik , Z. Pribulova , C. Marcenat , T. Klein , P. Rodiere , L. Cario , P. Samuely