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Tsague Fotio Carlos

Publications and source records attributed to Tsague Fotio Carlos.

2 recordsLinked to original sources

Generation of renormalized quadratic coefficient in Landau theory: Implications for specific-heat jump calculations in high-temperature superconductors

In this work, Landau's theory is revisited by renormalizing quadratic coefficients derived from nonlinear polynomial equations to account for system dimensionality. In this respect, the generated coefficients, which include an intrinsic energy parameter specific to each material, enable precise specific-heat calculations for a range of high-temperature superconductors near the superconducting transition. To that end, the change in the specific heat jump is explained phenomenologically, which applies to any spatial arrangement and electron interactions that influence system symmetries. Moreover, effects leading to rapid, non-monotonic variation in the specific heat jump, $Δ{C_p}/T_{c}$, across the transition are examined, with particular emphasis on changes attributed to the Sommerfeld coefficient in the normal state. The considerable reduction, disappearance, or significant enhancement of the specific heat anomaly at the superconducting transition is quantitatively explained by incorporating strong fluctuation corrections to the Landau theory for low-dimensional systems. Furthermore, the evolution of specific-heat jumps with system dimensionality is analyzed, and the results are discussed in relation to experimental observations of specific-heat jumps in yttrium- and bismuth-based superconductors, as well as in zero-dimensional superconductors.

cond-mat.supr-con↗

Induced phase transitions and spontaneous symmetry breaking based on the renormalized Ginzburg-Landau theory

In this study, we present theoretical investigations of phase transitions and critical phenomena in materials through the lens of second-order Ginzburg-Landau theory, in conjunction with considerations of symmetry groups and thermal fluctuations. By addressing the residual effects after a renormalization process, a small number of macroscopic degrees of freedom can effectively replace the infinite number of microscopic degrees of freedom, emphasizing the significant role of dimensionality and the intrinsic characteristics of the system in understanding and analyzing transitions. We highlight several non-universal characteristics of continuous phase transitions near the transition temperature, including the non-monotonic relationship between the critical temperature and dimensionality, as well as the enhancement or disappearance of the specific heat jump in complex superconductors. While the resulting expressions for thermodynamic quantities are complex for one-dimensional systems, obeying Mermin-Wagner's theorem, they are considerably simplified for two-dimensional and three-dimensional systems.

cond-mat.supr-con↗