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Related papers: Coherence lengths and anisotropy in MgB2 supercond…

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We study the fluctuation conductivity of a superconducting film, which is placed to perpendicular non-uniform magnetic field with the amplitude $H_0$ induced by the ferromagnet with domain structure. The conductivity tensor is shown to be…

Superconductivity · Physics 2015-06-11 S. V. Mironov , A. S. Mel'nikov

The angular dependence of the upper critical field Hc2 of MgB2 single crystals is studied at various temperatures by means of specific heat and transport measurements in magnetic fields up to 17 T. Clear deviations from Ginzburg-Landau…

The MgB2 superconductor synthesized in a flowing argon atmosphere using nanometer magnesium powder as the raw materials, denoted as Nano-MgB2, has been studied by the technique of in-situ high temperature resistance measurement (HT-RT…

Superconductivity · Physics 2009-11-10 Chinping Chen , Zeng-jun Zhou , Xing-guo Li , Jun Xu , Yu-hao Wang , Yong-zhong Wang , Qing-rong Feng

We study the peculiarities of coherency in a two-gap superconductor. The both intraband couplings, inducing superconductivity in the independent bands, and interband pair-transfer interaction have been taken into account. On the basis of…

Superconductivity · Physics 2012-06-28 Teet Örd , Küllike Rägo , Artjom Vargunin

It is demonstrated by SQUID magnetization measurements that (Ga,Mn)As films can exhibit rich characteristics of magnetic anisotropy depending not only to the epitaxial strain but being strongly influenced by the hole and Mn concentration,…

We have measured the longitudinal resistivity and the Hall resistivity in the ab-plane of highly c-axis-oriented MgB2 thin films. In the normal state, the Hall coefficient (R_H) behaves as R_H ~ T with increasing temperature (T) up to 130 K…

Superconductivity · Physics 2009-11-07 W. N. Kang , Hyeong-Jin Kim , Eun-Mi Choi , Heon Jung Kim , Kijoon H. P. Kim , H. S. 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

The temperature dependent resistivity of Ba$_{1-x}$K$_x$Fe$_2$As$_2$ (x = 0.23, 0.25, 0.28 and 0.4) single crystals and the angle dependent resistivity of superconducting Ba$_{0.6}$K$_{0.4}$Fe$_2$As$_2$ single crystals were measured in…

Superconductivity · Physics 2009-11-13 Zhao-Sheng Wang , Hui-Qian Luo , Cong Ren , Hai-Hu Wen

The superconducting and structural properties of a series of Mg1-xAlxB2 samples have been investigated. X-ray diffraction results confirmed the existence of a structural transition associated with the significant change in inter-boron layer…

Superconductivity · Physics 2009-11-07 J. Y. Xiang , D. N. Zheng , J. Q. Li , L. Li , P. L. Lang , H. Chen , C. Dong , G. C. Che , Z. A. Ren , H. H. Qi , H. Y. Tian , Y. M. Ni , Z. X. Zhao

It is shown that the transition to the low temperature superconducting state in a 3D metal at high magnetic field is smeared dramatically by thermal fluctuation of the superconducting order parameter. The resulting superconducting-to-normal…

Superconductivity · Physics 2013-05-29 T. Maniv , V. Zhuravlev

We investigate the dependence of the order parameter profile, local and total susceptibilities on both the temperature and external magnetic field within the mean-filed Ginzburg-Landau Ising type model. We study the case of a film geometry…

Statistical Mechanics · Physics 2015-08-28 Daniel M. Dantchev , Vassil M. Vassilev , Peter A. Djondjorov

We studied the far-infrared reflectance of superconducting MgB2 in and out of equilibrium using pulsed synchrotron radiation. The equilibrium data can be described by a single energy gap at 2 Delta / hc = 43 cm-1. The fit improves slightly…

Superconductivity · Physics 2007-05-23 R. P. S. M. Lobo , J. J. Tu , Eun-Mi Choi , Hyeong-Jin Kim , W. N. Kang , Sung-Ik Lee , G. L. Carr

We report optimization of the synthesis parameters viz. heating temperature (TH), and hold time (thold) for vacuum (10-5 torr) annealed and LN2 (liquid nitrogen) quenched MgB2 compound. These are single-phase compounds crystallizing in the…

The microstructure of the MgB2 superconductor sintered at high temperature under a high pressure of about 3 GPa was investigated by using a high-resolution transmission electron microscope (HRTEM). The TEM images did not show any pores in…

We have measured the resistivity and the Seebeck coefficient of a MgB2 sintered sample. The temperature dependence of resistivity is fitted well by a generalized Bloch-Gruneisen equation with a Debye temperature of 1050 K. The Seebeck…

We present data on temperature-dependent anisotropy of the upper critical field of MgB$_2$ obtained from the analysis of measurements on high purity, low resistivity polycrystals. The anisotropy decreases in a monotonic fashion with…

Superconductivity · Physics 2009-11-07 Sergey L. Bud'ko , Paul C. Canfield

Superconducting properties of hypothetical simple hexagonal CaB2 are studied using the fully anisotropic Eliashberg formalism based on electronic and phononic structures and electron-phonon interactions which are obtained from ab initio…

Superconductivity · Physics 2009-09-17 Hyoung Joon Choi , Steven G. Louie , Marvin L. Cohen

We present the anisotropic optical conductivity of MgB$_{2}$ between 0.1 and 3.7 eV at room temperature obtained on single crystals of different purity by the spectroscopic ellipsometry and reflectance measurements. The bare (unscreened)…

Superconductivity · Physics 2013-01-24 V. Guritanu , A. B. Kuzmenko , D. van der Marel , S. M. Kazakov , N. D. Zhigadlo , J. Karpinski

We report the growth of high-quality c-axis-oriented epitaxial MgB2 thin films by using a pulsed laser deposition technique. The thin films grown on (1`1 0 2) Al2O3 substrates show a Tc of 39 K. The critical current density in zero field is…

Superconductivity · Physics 2009-11-07 W. N. Kang , Hyeong-Jin Kim , Eun-Mi Choi , C. U. Jung , Sung-Ik Lee

Considerable excitement has been caused recently by the discovery that the binary boride system with stoichiometry MgB2 is superconducting at the remarkably high temperature of 39 K (1). This potentially opens the way to even higher Tc…

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