磁场退火对La_(0.7)Sr_(0.3)MnO_3低场磁电阻增强效应的研究

Research on the enhanced magnetoresistive response in magnetic-annealed La_(0. 7) Sr_(0. 3) MnO_3

为了提高La0.7Sr0.3MnO3的低场磁电阻效应,将样品进行了磁场退火处理。实验结果表明,磁场退火并没有改变样品的磁矩,但对其磁各向异性产生了较大的影响。与零磁场下退火的样品相比,磁场退火样品的磁电阻明显提高。这种增强效应在低磁场下更加明显,在0.1 T的外磁场下,磁退火样品的磁电阻比零场退火的提高了140%。利用自旋极化隧穿机制解释了这种增强的磁电阻效应。

Polycrystalline perovskite La0.7 Sr0.3 MnO 3 was annealed under magnetic field in order to increase the low-field magnetoresistance effect.The experimental results show that the magnetic annealing would not affect the magnetic moments but remarkably change the magnetic anisotropy of the sample.Compared with the per-ovskite without magnetic annealing,the magnetic-annealed La0.7 Sr0.3 MnO 3 exhibits large magnetoresistance effect,which can be more obviously observed in low magnetic field.At room temperature,a 140% enhancement of magnetoresistance response at 0.1 T was observed in the magnetic-annealed sample,which can be explained with the mechanism of spin-polarized intergrain tunneling.