Superconductivity in the calcium-decorated hexagonal boron nitride monolayer

• Published in: Journal of magnetism and magnetic materials 2022-04, Vol.548, p.168927, Article 168927
• Main Author: Drzazga-Szczȩśniak, Ewa
• Format: Article
• Language: English
• Subjects: BCS theory; Boron nitride; Calcium; Electron–phonon interaction; Energy gap; Liquid helium; Phonons; Superconductivity; Superconductors; Thermodynamic properties; Thermodynamics; Transition temperature; Two-dimensional materials
• ISSN: 0304-8853; 1873-4766
• DOI: 10.1016/j.jmmm.2021.168927

In the present paper, we study the pivotal thermodynamic properties of the novel two-dimensional calcium-decorated hexagonal boron nitride superconductor. The analysis is motivated by the ongoing and growing interests in the two-dimensional superconductors and the fact that the discussed material is expected to exhibit relatively high critical temperature, which is well above the temperature of the liquid helium. The presented investigations are performed within the state-of-art Eliashberg formalism, according to the potential phonon-mediated strong-coupling character of the considered superconducting state. In particular, we calculate the thermodynamic properties that allow us to quantitatively determine values of the characteristic dimensionless parameters i.e. the zero-temperature energy gap to the critical temperature, the ratio for the specific heat, as well as the ratio corresponding to the critical magnetic field. The obtained result show that the discussed superconducting state is strongly influenced by the strong electron–phonon interactions as well as the retardation effects and cannot be adequately described within the Bardeen–Cooper–Schrieffer theory. This is to say, the analyzed material is yet another example of the two-dimensional superconducting crystal that may be of potential importance for the development of superconducting low-dimensional devices. •The superconducting state in Ca-decorated hBN is examined.•The Eliashberg formalism is employed to determine the thermodynamic properties.•The observed thermodynamic properties strongly deviates from the Bardeen–Cooper–Schrieffer theory.