Negative Oxygen Isotope Effect on the Static Spin Stripe Order in Superconducting La2-x,BaxCuO4(x=1/8) Observed by Muon-Spin Rotation

Large negative oxygen-isotope (O-16 and O-18) effects (OIEs) on the static spin-stripe-ordering temperature T-so and the magnetic volume fraction V-m were observed in La2-xBaxCuO4(x = 1/8) by means of muon-spin-rotation experiments. The corresponding OIE exponents were found to be a(TBO) = 0.57(6) and a(Vm) = 0.71(9), which are sign reversed to a(Tc) = 0.46(6) measured for the superconducting transition temperature T-c. This indicates that the electron-lattice interaction is involved in the stripe formation and plays an important role in the competition between bulk superconductivity and static stripe order in the cuprates.