Abstract
By means of first-principles cluster expansion, anisotropic superconductivity in the transition metal dichalcogenide Nb(Se_{x}S_{1-x})_{2} forming a van der Waals (vdW) layered structure is observed theoretically. We show that the Nb(Se_{0.5}S_{0.5})_{2} vdW-layered structure exhibits minimum ground-state energy. The Pnnm structure is more thermodynamically stable when compared to the 2H–NbSe_{2} and 2H–NbS_{2} structures. The characteristics of its phonon dispersions confirm its dynamical stability. According to electronic properties, i.e., electronic band structure, density of states, and Fermi surface indicate metallicity of Nb(Se_{0.5}S_{0.5})_{2}. The corresponding superconductivity is then investigated through the Eliashberg spectral function, which gives rise to a superconducting transition temperature of 14.5 K. This proposes a remarkable improvement of superconductivity in this transition metal dichalcogenide.
Highlights
By means of first-principles cluster expansion, anisotropic superconductivity in the transition metal dichalcogenide Nb(SexS1−x)[2] forming a van der Waals layered structure is observed theoretically
Experimental observation has pointed out that there is an interplay between Charge-density waves (CDWs), Fermi surface topology (FST), and superconductivity for the anisotropy in the electron-phonon coupling (EPC) and Fermi velocities that the EPC and multiband structure of the FST are crucial for s uperconductivity[17]
Regarding the structure of Nb(SexS1−x)[2 ], we began by determining the ground-state structures of Nb(SexS1−x)[2 ], where x = 0.5, and compared their energies with those of 2H-NbSe2 and 2H-NbS2. We study their electronic properties, i.e., electronic band structure, Fermi surface, and Eliashberg spectral function that are directly related with the superconductivity of the materials
Summary
By means of first-principles cluster expansion, anisotropic superconductivity in the transition metal dichalcogenide Nb(SexS1−x)[2] forming a van der Waals (vdW) layered structure is observed theoretically. The corresponding superconductivity is investigated through the Eliashberg spectral function, which gives rise to a superconducting transition temperature of 14.5 K This proposes a remarkable improvement of superconductivity in this transition metal dichalcogenide. CDW was found to improve superconductivity in such an electron-phonon coupled system of the 2H-NbSe2 structure[13]. According to the local magnetic field, T c accounting for both the 2H-NbS2 and 2H-NbSe2 structures reported to be approximately 5.6 K and 7.2 K, respectively At this point, the FST calculation is a key factor for superconductivity, which demonstrates a positive correlation between T c and pressure. The atomicsubstitution method plays an important role in improving superconductivity in this class of materials which have been demonstrated by both ab initio anisotropic ME theory and the F ST17,18,20,21
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