Giant Oxygen Isotope Effect in Charge-Ordered Manganese Perovskites

Spectacular oxygen isotope (18O) enhancement of charge-ordering temperatures is reported in manganese perovskites Nd0.5Sr0.5MnO3and La0.5Ca0.5MnO3. The isotope shift of charge-ordering temperatures was found to increase with increasing average radius of the A-site cations, and A-site size disorder parameter,2. While Nd0.5Sr0.5MnO3with the largest and2in this study showed an isotope shift as high as 21 K, Pr0.5Ca0.5MnO3with the smallest and2remained virtually unaffected by18O exchange.