Effect of uniaxial stress on critical temperatures of superconducting cuprates: an indirect-exchange approach

A recent paper by Locquet et al. [Nature 394 (1998) 453], reporting a doubling of the critical temperature TCr in La1.9Sr0.1CuO4 (from 25 to 49 K) using uniaxial stress, has aroused speculations of reaching much higher TCr values than the present maximum (134 K in a mercury cuprate). From a critical analysis, applying concepts of an earlier proposed indirect-exchange approach to high-temperature superconductivity (HTSC), we conclude that a substantial increase of TCr is theoretically restricted to systems with a low initial TCr. Implications for the theory of HTSC inferred in the paper quoted from data on c-axis compression versus TCr are shown to be invalid.