• Journal of the Korean Physical Society
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• 제73권10호
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• pp.1550-1554
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• 2018

The spin cutoff parameters of $^{50-57}Cr$ isotopes have been calculated using a superconducting Hamiltonian with the inclusion of the pairing effect. Their energy and temperature dependences have been studied through comparison with some well-known semi-empirical formulae. This study shows that the microscopic calculation results converge to the Fermi gas model prediction at higher energies. Also, an even-odd effect is evident in the spin cutoff parameters at low temperatures and disappears after the pairing phase transition.

• 한국초전도ㆍ저온공학회논문지
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• 제26권2호
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• pp.9-18
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• 2024

The current study deals with the possible interplay between superconductivity and spin density wave in two band model high temperature iron based superconductor (FeBSC) Ba_1-xNa_xFe₂As₂. The electron and hole bands in the presence of the inter-band interaction between the two bands is becoming a vital issue to deal with the high temperature physics of the iron-based superconductors. In this research work, a model Hamiltonian appropriate for the system under consideration has been developed and the temperature dependent Green's function technique has been employed to get the solution for the equations of motion constructed for the two band model high temperature FeBSC Ba_1-xNa_xFe₂As₂. By making use of the decoupling procedure, the equations of motion for the dependence of superconducting transition temperature (T_C) on spin density wave(SDW) order parameter (Δ_SDW) in the electron intra-band (Δ_sc(e)) , hole intra-band (Δ_sc(h)) and inter-band (Δ_sc(eh)) for Ba_1-xNa_xFe₂As₂ have been obtained. We have also obtained the expression for the dependence of spin density wave transition temperature(T_SDW) on Δ_SDW for Ba_1-xNa_xFe₂As₂. Using some plausible approximations and appropriate experimental values for the parameters in the obtained equations of motion, phase diagrams of T_C versus Δ_sc(e), Δ_sc(h) and Δ_sc(eh) are plotted. Furthermore, a phase diagram of T_SDW versus Δ_SDW is plotted for the material under consideration. Finally, using the above mentioned phase diagrams, the interplay between superconductivity and spin density wave in the two band model high temperature FeBSC Ba_1-xNa_xFe₂As₂ has been demonstrated to be a very distinct possibility. The agreement of the current finding with the experimental observations is quite commendable.