Characterization of Novel High-Pressure Close-Packed Superconducting Phase of Boron

We report study on the thermodynamic properties of the novel high-pressure superconducting phase of boron with hexagonal P6₃/mcm structure. Our analysis is conducted at the pressure of p=400 GPa, which is motivated by the highest value of the superconducting transition temperature $(T_{C})$ observed previously under such conditions for the P6₃/mcm boron. Our investigations of the thermodynamic properties are performed within the Eliashberg formalism, due to the strong-coupling character of the considered material. In particular, we calculate the thermodynamic properties of the superconducting state which allows us to determine the values of the characteristic dimensionless parameters; the zero-temperature energy gap to the critical temperature, the ratio of the specific heats, as well as the ratio connected with the zero-temperature thermodynamic critical field.