Spin gap in the normal state of Pr-doped and oxygen-deficient superconductors

The spin-gap temperatures (Formula presented) in the normal state of bulk Pr-doped (Formula presented) and oxygen-deficient (Formula presented) ((Formula presented) Er, Y, Ho, Dy, Gd, Eu, Sm, and Nd) are investigated. The elements on the R sites and the distance between (Formula presented) planes are found to have no influence on (Formula presented) in oxygen-deficient (Formula presented) in terms of the relationship between the superconducting temperature (Formula presented) and (Formula presented) However, for (Formula presented) increases with increasing ionic size of R-site elements for a fixed Pr concentration. Furthermore, by comparing (Formula presented) of oxygen-deficient (Formula presented) to that of (Formula presented) at the same (Formula presented) it is observed that Pr atoms doped on the R sites not only reduce the carrier density and induce the spin gap, but will also simultaneously suppress (Formula presented).