Oxygen-isotope effect on the in-plane penetration depth in underdoped Y_{1-x}Pr_xBa_2Cu_3O_{7-delta} as revealed by muon-spin rotation

Abstract

The oxygen-isotope (^16O/^18O) effect (OIE) on the in-plane penetration depth ${\lambda }_{ab}(0)$ in underdoped Y_{1-x}Pr_xBa_2Cu_3O_{7-delta} was studied by muon-spin rotation. A pronounced OIE on ${\lambda }_{ab}^{-2}(0)$ was observed with a relative isotope shift of $\Delta {\lambda }_{ab}^{-2}/{\lambda }_{ab}^{-2}$=-5(2)% for x =0.3 and -9(2)% for x=0.4. It arises mainly from the oxygen-mass dependence of the in-plane effective mass $m_{ab}^{\ast }$. The OIE exponents of T_{c} and of ${\lambda }_{ab}^{-2}(0)$ exhibit a relation that appears to be generic for cuprate superconductors.

4 pages, 4 eps figures, RevTex4