Study of the superconducting state in the Cmmm phase of GeH4 compound

The superconducting state, that gets induced in the GeH4 compound under the pressure at 20 GPa, is characterized by the high critical temperature T-C(mu(star))is an element of < 54.5, 31.2 > K where mu(star) is the Coulomb pseudopotential, and mu(star)is an element of < 0.1, 0.3 >. Other thermodynamic parameters for the considered range of the Coulomb pseudopotential significantly differ from the predictions of the BCS model. In particular: (i) the ratio of the energy gap to the critical temperature (R-Delta equivalent to 2 Delta(0)/k(B)T(C)) changes from 4.07 to 3.88; (ii) the value of the parameter R-C equivalent to Delta C(T-C)/C-N(T-C) decreases from 1.85 to 1.69, where Delta C denotes the specific heat jump, and C-N is the specific heat of the normal state; (iii) the ratio R-H equivalent to TCCN(T-C)/H-C(2)(0) increases from 0.147 to 0.155; H-C represents the thermodynamic critical field. (c) 2013 Elsevier Ltd. All rights reserved.