【摘要】 研究了电子型掺杂钙钛矿薄膜La_1-xCe_xMnO₃的输运性质和外场作用下的输运机理。研究表明,La_1-xCe_xMnO₃薄膜呈现出典型的金属-绝缘体转变,且与Ce的掺杂浓度相关。电阻-温度曲线表明,在低温时,电子-电子散射和磁畴对电子的散射是电阻形成的主要原因,而在高温下,小极化子的跳跃机制起主要作用。通过激光照射样品表面,发现光场诱导金属-绝缘体转变温度向着低温区偏移,该现象产生的原因在于La_1-xCe_xMnO₃薄膜内部铁磁相与顺磁相的共存,此外,高能量的激光对样品的电阻变化影响更明显。进一步研究表明,Ce的掺杂浓度将会通过金属-绝缘相变对La_1-xCe_xMnO₃薄膜的磁电阻效应产生显著的调制作用。更多还原

【Abstract】 We performed the experimental studies on La_1-xCe_xMnO₃ to investigate transport properties and field-induced transport mechanisms in electronic doped perovskite films. La_1-xCe_xMnO₃ films exhibit significant metal-insulator transition, which can be modulated by the doping ratio of Ce. Resistance-temperature curves indicate that the magnetic domains and electron-electron scattering mainly contribute to the transport mechanism in the low temperature region, while the hopping conduction of small polaron becomes the dominating factor at the high temperatures. Laser irradiation is found to induce the shift of metal-insulator transition temperature towards the lower temperature region due to the coexistence of ferromagnetic（FM） metallic phase and paramagnetic（PM） insulating phase in La_1-xCe_xMnO₃ films. The higher laser intensity gives rise to more significant change in resistance. Furthermore, magnetoresistance effect can be affected by different doping ratios of Ce in La_1-xCe_xMnO₃ films because of the MIT transition.更多还原