Non-BCS superconducting state in yttrium hydride at a record low value of the external pressure

作者：Jarosik Marcin W; Szczesniak Radoslaw; Wrona Izabela A; Kostrzewa Malgorzata

来源：Solid State Communications, 2017, 250: 5-8.

DOI：10.1016/j.ssc.2016.11.002

• Superconductivity
• Pressure
• Yttrium hydride

The ab initio calculations suggest that YH3 compound is a superconductor with the maximum value of the critical temperature (T-C) for the record low external pressure equal to 17.7 GPa. Due to the high value of the electron phonon coupling constant, the thermodynamic properties of the superconducting state in YH3 have been determined in the framework of the Eliashberg formalism. It has been shown that T-C changes in the range from 45.91K to 27.29 K, for the value of the Coulomb pseudopotential mu* is an element of < 0.1, 0.3 >. The parameters of the superconducting phase differ significantly from the values predicted by the BCS theory due to the significant strong-coupling and retardation effects: k(B)T(C)/omega(ln) is an element of < 0.138, 0.082 >, where coin denotes the logarithmic phonon frequency. In particular, the dimensionless ratios: R-Delta = 2 Delta (0)/k(B)T(C), R-C = Delta C (T-C)/C-N (T-C) and R-H = TCCN (T-C)/H-C(2)(0) take the following values: R Delta is an element of < 4.38, 4.20 >, R-C is an element of < 2.18, 2.02 > and R-H is an element of < 0.151, 0.168 >. The symbol A represents the order parameter, Delta C is the specific heat jump, Cm is the specific heat of the normal state, and H-C is the thermodynamic critical field.

• 出版日期2017-1