Non-zero Isotope Effect in La sub (1.85) Sr sub (0.15) CuO sub 4.
01 January 1987
The effect on the superconducting transition temperature of exchanging sup (18) O for sup (16) O in La sub (1.85) Sr sub (0.15) CuO sub 4 has been studied. The concentration of the two isotopes has been determined by Rutherford Backscattering Spectroscopy and Raman spectroscopy confirmed the mass-related phonon frequency shift. The sup (18) O substitution is found to be the same on the two O sites. Magnetic measurements of the transition temperature reveal a non-zero isotope effect (alpha = 0.16 +- 0.02). The exponent alpha has also been calculated within a conventional electron-phonon interaction model and was found to be significantly larger.