Negative Oxygen Isotope Effect on the Static Spin Stripe Order in   La_(2-x)Ba_xCuO_4 (x = 1/8)
  Large negative oxygen-isotope (16O/18O) effects (OIE's) on the static spin-stripe ordering temperature T_so and the magnetic volume fraction V_m were observed in La_(2-x)Ba_xCuO_4 (x = 1/8) by means of muon spin rotation experiments. The corresponding OIE exponents were found to be alpha_(T_so) = -0.57(6) and alpha_(V_m) = -0.71(9), which are sign reversed to alpha_(T_c) = 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. 
Z. Guguchia, R. Khasanov, M. Bendele, E. Pomjakushina, K. Conder, A.   Shengelaya, and H. Keller
cond-mat.supr-con