arXiv subjects

A. Changjan

Publications and source records attributed to A. Changjan.

4 recordsLinked to original sources

arXiv2023

The investigation of the hydride superconductor's parabolic-like critical temperature under high pressure

Under the weak coupling, we investigate the critical temperatures under pressure of H3S, LaH10, CaH6, and Tl2Ba2CaCu2O8+{\delta} superconductors. The superconducting mechanism takes into account the electron-phonon interaction as well as the Coulomb interaction. Under high pressure, the critical temperature equation is calculated as a function of the fractional volume of the unit cell, and the Birch-Murnaghan equation of state is used to determine the relationship between fraction volume and pressure. Using this equation, we can analyze the parabolic-like relationship between the critical temperature and pressure of a superconductor. The parabolic behavior of these superconductors' critical temperature versus pressure can fit well. The maximal critical temperature of Tl2Ba2CaCu2O8+{\delta}, H3S, LaH10, and CaH6 superconductors are predicted to be 112 K at 7 GPa, 197 K at 140 GPa, 252 K at 143 GPa, and 207 K at 174 GPa, respectively.

cond-mat.supr-con↗

arXiv2011

The Critical Magnetic Field of Anisotropic Two-Band Magnetic Superconductors

The upper and lower critical field, and the critical field ratio of an anisotropic two-band magnetic superconductors in Ginzburg-Landau(GL) scenery is derived analytically. The temperature-dependent on the upper critical field is investigated and applied to Fe-based superconductors. We find that the very high value of zero-temperature upper critical field in Fe-based superconductors can be found in the negative differential susceptibility region. The temperature-dependent upper critical field is presented in two formulas as in the empirical view and in the GL two-band view that agrees with the experiment results.

cond-mat.supr-con↗

arXiv2010

Critical Magnetic Field Ratio of Anisotropic Magnetic Superconductors

The upper critical field, the lower critical field and the critical magnetic field ratio of anisotropic magnetic superconductors are calculated by Ginzburg-Landau theory analytically. The effect of the Ginzburg-Landau parameter(κ_0), magnetic susceptibility(χ) and magnetic-to- anisotropic parameter ratio(θ) on the critical field ratio are considered. We find that the value of critical magnetic field ratio with χ< 0, higher κ_0,and higher θcase are shown the higher value. And, the diamagnetic superconductors with highly anisotropic and the ferromagnetic superconductors are shown the highest and the lowest, respectively.

cond-mat.supr-con↗

arXiv2005

Hc2 of anisotropy two-band superconductors by Ginzburg-Landau approach

The purpose of this research is to study the upper critical field (Hc2) of two-band superconductors by two-band Ginzburg - Landau approach. The analytical formula of Hc2 included anisotropy of order parameter and anisotropy of effective-mass are found . The parameters of the upper critical field in ab-plane and c-axis can be found by fitting to the experimental data . Finally, we can find the ratio of upper critical field that temperature dependent in the range of experimental result .

cond-mat.supr-con↗