arXiv subjects

P. Udomsamuthirun

Publications and source records attributed to P. Udomsamuthirun.

13 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+δ 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+δ, 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↗

arXiv2019

The study on penetration depth of anisotropic two-band s-wave superconductors by Ginzburg-Landau approach

The penetration depth of anisotropic two-band s-wave superconductors have been studied by Ginzburg-Landau approach. The anisotropic spherical Fermi surfaces and order parameters with the spherical ellipse or pancake Fermi shape are used for derive penetration depth equation. The numerical calculation of pancake-pancake and pancake-ellipse Fermi sphere shape are fits well with the experiment data of MgB2 and CaAlSi superconductor, consequently. Our model should be the way to increase understanding in the microscopic mechanism of occurrence of the penetration depth in superconductivity state of these material

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↗

arXiv2009

The possible superconductivity at 109 K in YBaCuO materials

The new YBaCuO superconductors are synthesized by using the standard solid state reaction method as Y5-6-11, Y7-9-16, Y5-8-13, Y7-11-18, Y156, Y3-8-11, and Y13-20-23. We find that all material obtained are shown the Meissner effect at 77 K. The resistivity measurements are used by the four-probe method .The Y 7-11-18 has the highest onset as 109 K . The XRD spectra are shown that they have the same crystal structure as Y123 with some impurities peaks .

cond-mat.supr-con↗

arXiv2009

Effect of Impurities Scattering Potential on NMR relaxation rate in impure d-wave superconductors

The purpose of our research is to study the nuclear spin lattice relaxation rate of impure d-wave superconductors. We use the Green function method to derive the approximation equation of density of states including the impurity scattering potential. We can get the analytic equation of the nuclear spin lattice relaxation rate that contained the impurity scattering potential in case of weak scattering potential and strong scattering potential in the simple form as the power series of order parameter and temperature . The numerical calculations show that there is coherence peak in the weak impurity scattering potential but there is no peak in the strong impurity scattering potential.

cond-mat.supr-con↗

arXiv2009

Investigate the effect of anisotropic order parameter on the specific heat of anisotropic two-band superconductors

The effect of anisotropic order parameter to specific heat of anisotropic two-band superconductors in BCS weak-coupling limit are investigated. An analytical specific heat jump and the numerical specific heat are shown by using anisotropic order parameters, and the electron-phonon interaction and non-electron-phonon interaction. The two model of anisotropic order parameters are used for numerical calculation that we find little effect to the numerical results . The specific heat jump of, and superconductors can fit well with the both of them. By comparing to experimental data overall range of temperature, the best fit is ,, and superconductors, respectively.

cond-mat.supr-con↗

arXiv2009

The ratio of normal state to superconducting state of spin lattice relaxation rate of unconventional superconductors

In this research, we derive a simple expression for the ratio of normal state superconducting state of spin lattice relaxation rate of unconventional superconductors from the BCS weak-coupling equation. The unconventional superconductors we consider have three types of order parameters as d-wave, 3He A-phase and p-wave 3-dimensional order parameter that had been done before by Parker and Haas[7].After using some numerical approximations and some boundary conditions, we can find the ratio of normal state to superconducting state of spin lattice relaxation rate in power series of temperature dependent order parameters and temperature. Our numerical calculations show the coherence peak below critical temperature clearly that are consistent with Parker and Haas[7]. These results do not agree with the believed that the coherence peak is the only property of s-wave superconductor. However from our calculation, we can conclude that the unconventional superconductors can show the coherence peaks.

cond-mat.supr-con↗

arXiv2008

The spin exchange interaction effect on Tc equation of anisotropic impure superconductors

We study the influence of spin exchange interaction of impurity scattering on critical temperature of anisotropic impure superconductors. The model of random nonmagnetic and magnetic impurity are revised to cover the effect of spin exchange interaction . The sign of magnitude of the second-order Born scattering have been changed after consideration the spin exchange interaction effect that also effect to form of Tc equation. We can get the general Tc equation that can be described anisotropic impure superconductors well and cover all model done before.

cond-mat.supr-con↗

arXiv2006

Influence of impurity on isotope coefficient of superconductors

We study the influence of anisotropy of the impurity potential on isotope coefficient of an impure superconductor in Born limit. From the isotope coefficient of non-magnetic and magnetic impurities including an angle-resolved Fermi surface density of state, anisotropy order parameter and impure potential, we make the assumption that the form of them are in the harmonic form and are investigated. Our numerical calculation of isotope coefficient can fit well with experimental data of high-Tc superconductors.

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↗

arXiv2005

Effect of density of state on isotope effect exponent of two-band superconductors

The exact formula of Tc's equation and the isotope effect exponent of two-band s-wave superconductors in weak-coupling limit are derived by considering the influence of two kinds of density of state : constant and van Hove singularity. The pairing interaction in each band consisted of 2 parts : the electron-phonon interaction and non-electron-phonon interaction are included in our model. We find that the interband interaction of electron-phonon show more effect on isotope exponent than the intraband interaction and the isotope effect exponent with constant density of state can fit to an experimental data,MgB2, and high-Tc superconductors, better than van Hove singularity density of state.

cond-mat.supr-con↗

arXiv2004

Influence of interband interaction on Isotope Effect Exponent of MgB2 Superconductors

The exact formula of Tc's equation and the isotope effect exponent of two-band s-wave superconductors in weak-coupling limit are derived by considering the influence of interband interaction. The paring interaction in each band consisted of 2 parts : the electron-phonon interaction and non-phonon interaction are included in our model. The isotope effect exponent of MgB2 equal to 0.3 with Tc 40 K can be found in the weak coupling regime and interband interaction of electron-phonon interaction show more effect on isotope effect exponent than of non-phonon interaction.

cond-mat.supr-con↗