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We report on specific heat, high magnetic field transport and $ac-$susceptibility measurements on magnesium diboride single crystals. The upper critical field $H_{c2}$ for magnetic fields perpendicular and parallel to the Mg and B planes is…

We present an improved analysis of the phase transitions in rare earth superconductor using Ginzburg-Landau theory. Our work is based on the systematic study of critical field and superconducting order parameter in the presence of localized…

Materials Science · Physics 2021-01-19 Preeti Suman Dash , Salila Das , Prabir K. Mukherjee

Self-consistent solutions of the Ginzburg-Landau system of equations, which describe the order parameter and the magnetic field distribution in a long superconducting cylinder of finite radius R, in external magnetic field H, when vortex…

Superconductivity · Physics 2007-05-23 G. F. Zharkov , V. G. Zharkov , A. Yu. Zvetkov

The conjecture that $N=2$ minimal models in two dimensions are critical points of a super-renormalizable Landau-Ginzburg model can be tested by computing the path integral of the Landau-Ginzburg model with certain twisted boundary…

High Energy Physics - Theory · Physics 2010-04-07 Edward Witten

By comparison of recent direct measurements of the temperature dependence of the upper critical field $H_{c2}$ in an Y-123 high temperature superconductor with the scaling analysis of magnetization data, collected in fields H << H_c2, we…

Superconductivity · Physics 2008-06-09 I. L. Landau

Using the microscopic formalism of Eilenberger equations, a three-band Ginzburg-Landau theory for the intraband dirty limit and clean interband scattering case is derived. Within the framework of this three-band Ginzburg-Landau theory,…

Superconductivity · Physics 2013-10-25 Y. Yerin , S. -L. Drechsler , G. Fuchs

The Landau potential in the general Ginzburg-Landau theory with two order parameters and all possible quadratic and quartic terms cannot be minimized with the straightforward algebra. Here, a geometric approach is presented that circumvents…

Superconductivity · Physics 2013-05-29 I. P. Ivanov

It is well known that a four-fold symmetry of the parallel upper critical magnetic field disappears in the Ginzburg-Landau (GL) region in quasi-two-dimensional (Q2D) $d$-wave superconductors. Therefore, it has been accurately calculated so…

Superconductivity · Physics 2020-07-15 Andrei G. Lebed

The bulk upper critical field H_{c2}(T) of superconducting MgB_2 and its anisotropy are established by analyzing experimental data on the temperature and magnetic field dependences of the ab-plane thermal conductivity of a…

Superconductivity · Physics 2009-11-07 A. V. Sologubenko , J. Jun , S. M. Kazakov , J. Karpinski , H. R. Ott

High-quality single crystal of Ca0.8La0.2Fe0.98Co0.02As2 has been successfully synthesized using a self-flux method. The magnetization measurement reveals a second peak effect and high critical current density exceeding 2*10^6 A/cm2 at 5…

Superconductivity · Physics 2016-04-01 Xiangzhuo Xing , Wei Zhou , Nan Zhou , Feifei Yuan , Yongqiang Pan , Haijun Zhao , Xiaofeng Xu , Zhixiang Shi

Many critical properties of the Hintermann-Merlini model are known exactly through the mapping to the eight-vertex model. Wu [J. Phys. C {\bf 8}, 2262 (1975)] calculated the spontaneous magnetizations of the model on two sublattices by…

Statistical Mechanics · Physics 2015-06-05 Chengxiang Ding , Yancheng Wang , Wanzhou Zhang , Wenan Guo

We show that the upper critical field in nanometer-sized Nb particles is governed by the changes in the effective Ginzburg-Landau coherence length occurring due to two competing factors: (i) the decrease in the grain size and consequent…

Mesoscale and Nanoscale Physics · Physics 2007-05-23 Sangita Bose , Pratap Raychaudhuri , Rajarshi Banerjee , Pushan Ayyub

The superconducting upper critical field $H_{c2}(T)$ of a two dimensional BCS superconductor is calculated in the vicinity of a van-Hove singularity. The zero temperature upper critical field is strongly enhanced at weak coupling when the…

Condensed Matter · Physics 2009-10-28 R. G. Dias , J. M. Wheatley

We develop a theory of the upper critical field in a BCS superconductor with a nonlocal interaction between electrons. We have shown that the nonlocal interaction is characterized by the parameter $k_F\rho_0$ where $k_F$ is the Fermi…

Superconductivity · Physics 2016-12-21 A. V. Shumilin , V. V. Baranov , V. V. Kabanov

A scalar model is built, as a quantum field theory defined on toroidal topologies, to describe phase transition in films subjected to periodic boundary conditions and influenced by an external and constant magnetic field. Criticality is…

Statistical Mechanics · Physics 2017-12-12 Erich Cavalcanti , Erick Castro , Cesar A. Linhares , Adolfo P. C. Malbouisson

This article develops a global existence result for the solution of an optimal control problem associated to the Ginzburg-Landau system. This main result is based on standard tools of analysis and functional analysis, such as the Friedrichs…

Optimization and Control · Mathematics 2019-02-13 Fabio Botelho , Eduardo Pandini Barros

We develop a numerical method suitable for gravitational collapse based on Cauchy evolution with an ingoing characteristic boundary. Unlike similar methods proposed recently (Ripley; Bieri, Garfinkle & Yau 2019/20), the numerical grid…

General Relativity and Quantum Cosmology · Physics 2020-12-04 Oliver Rinne

Ginzburg-Landau model with two order parameters appears in many condensed-matter problems. However, even for scalar order parameters, the most general U(1)-symmetric Landau potential with all quadratic and quartic terms contains 13…

Other Condensed Matter · Physics 2015-02-18 I. P. Ivanov

Consistent perturbation theory for thermodynamical quantities in strongly type II superconductors in magnetic field at low temperatures is developed. It is complementary to the existing expansion valid at high temperatures. Magnetization…

Condensed Matter · Physics 2009-10-31 H. C. Kao , B. Rosenstein , J. C. Lee

We study the Ginzburg-Landau model of superconductivity in three dimensions and for strong external magnetic fields. For magnetic field strengths above the phenomenologically defined second critical field it is known from Physics that…

Mathematical Physics · Physics 2011-10-20 S. Fournais , A. Kachmar , M. Persson
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