Oxygen-deficiency-activated charge ordering in La2/3Sr1/3MnO3-δ thin films

Abstract

The oxygen-deficiency-activated charge ordering (CO) transition has been observed in C-oriented La2/3Sr1/3MnO3-δ thin films prepared by pulsed laser deposition on LaAIO3 substrates. A rapid growth of the sample resistivity at temperatures below TC is observed, while significant thermal hysteresis and electrical field induced transition from the insulator CO state to metallic-like state are recorded. Such a CO state can also be partially melted under a magnetic field of 0.4 T, resulting in enhanced magnetoresistance at low temperatures. Magnetic properties of the films can be well understood as the coexistence of the ferromagnetic state and the CO state. The CO state in oxygen deficient thin films is explained in terms of the Mn-O octahedral distortion or the narrowness of the conduction bandwidth of the eg carriers. © 2000 American Institute of Physics.