A POSSIBLE SOLITON-LIKE POLARON MODEL FOR SUPERCONDUCTORS Y_1-xCa_xBa₂Cu_3-xM_xO_7-\delta(M=Fe, Ni)

Using 1+1 soliton-like polaron model of a deformable continuum, the critical temperature and the energy gap in high-temperature superconductors Y_1-xCa_xBa₂Cu_3-xM_xO_7-\delta(M=Fe, Ni) are studied in the framework of finite temperature Green's function theory. The ratio 2\varDelta/k_BT_c=3.9 is obtained. Theoretical results are found in good agreement with the experimental data.