Single crystal La2/3Sr1/3MnO3-delta manganite with an unusual structure was obtained by the optical-floating method with controlled growth in a flowing argon atmosphere. A modulated twin-like structure with phase separation characteristics in the long-range order is found. The energy-dispersive X-ray spectroscopy measurement reveals that there is a strong chemical fluctuation for different stripes, i.e. resulting from the nonstoichiometry due to oxygen deficiency. After annealing, the twin-like stripe phase disappears and the single crystal shows excellent properties. These results may be of great significance for controlled growth of oxide electronics materials with artificial superstructure-like technique. (C) 2010 Elsevier B.V. All rights reserved.