A comparison of two high-pressure superconducting phases in yttrium

作者：Durajski Artur P^*

来源：Physica Status Solidi (B) Basic Research, 2015, 252(10): 2167-2173.

DOI：10.1002/pssb.201552180

• Eliashberg formalism
• high-pressure phases
• superconductors
• thermodynamic properties
• yttrium

Elemental yttrium under high pressure is discussed in the context of superconductivity with a phonon-mediated pairing mechanism. In particular, the strong-coupling Eliashberg theory of superconductivity is employed to determine the thermodynamic properties of two new phases hp3'P3121 and oF16'Fddd that Y may take at 97GPa. The comparative studies show that the critical value of the Coulomb pseudopotential equals 0.20 and 0.24 for hp3'P3121 and oF16'Fddd phases, respectively. This directly translates into a value of the energy gap at the Fermi level 2(0){6.92,6.66}meV and the electron effective mass at the critical temperature m(e)(*)/m(e) is an element of{2.752, 2.423}. Moreover, we proved that the dimensionless ratios connected with the critical temperature, the energy gaps, the specific heat, and the thermodynamic critical field are no longer universal and cannot be correctly described using the canonical Bardeen-Cooper-Schrieffer (BCS) theory due to the strong-coupling and retardation effects existing in the investigated systems.

• 出版日期2015-10