(La_(0.7)Sr_(0.3)MnO_3)_m(BiFeO_3)_n超晶格间隔的La_(0.7)Sr_(0.3)MnO_3三明治结构制备及表征

Fabrication and characterization of La_(0.7)Sr_(0.3)MnO_3 sandwich structure separated by(La_(0.7)Sr_(0.3)MnO_3)_m(BiFeO_3)_n superlattice

采用射频磁控溅射的方法在SrTiO3(001)基片上制备了(La0.7Sr0.3MnO3)m(BiFeO3)n超晶格间隔的La0.7Sr0.3MnO3三明治结构.X射线衍射分析证明(La0.7Sr0.3MnO3)m(BiFeO3)n具有明显的超晶格结构.电流垂直于薄膜表面测得的电阻-温度关系表明,(La0.7Sr0.3MnO3)m(BiFeO3)n超晶格薄膜在290K有金属-绝缘体转变,略低于单层La0.7Sr0.3MnO3薄膜的转变温度.电流在0.01—10mA范围内,观察到薄膜的峰值电阻随电流增大而减小,峰值变化率远大于单层La0.7Sr0.3MnO3薄膜,且随着超晶格周期厚度的增加而增大.低温下,电流-电压曲线表明其导电机制应主要为空间载子限制,且显示较大的电压偏置,表现出肖特基结的特性.

La0.7Sr0.3MnO3 sandwich structure separated by （La0.7Sr0.3MnO3）m（BiFeO3）n superlattices is grown in situ on SrTiO3 （001） substrates by RF magnetron sputtering. The X-ray diffraction scans indicate that the films are obviously superlattice structures. The resistivity-temperature curves measured in the case of current perpendicular to the plane geometry show that the films undergo metal-insulator transition at 290 K, which is a little lower than the temperature of single La0.7 Sr0.3 MnO3 film. When the current is within 0.01--10 mA, the peak resistivity of the （La0.7Sr0.3MnO3）m（BiFeO3）n films decreases with the increasing current. The change rate which is higher than that of single La0.7 Sr0.3 MnO3 film increases with the increasing thickness of the period films. The current-voltage curves indicate that the conduction mechanism in superlattices is space-charge-limited con-duction and a big bias voltage which is a characteristic of Schottky junction is also found in the current-voltage curves at low temperatures.