【摘要】 本文研究了不同温度下、磁场与具有双层结构的La1.4 Sr1.6Mn2 O7外延膜膜面成不同角度θ时的电子顺磁共振谱 ,并测量了此薄膜材料的输运性质 .发现在任一温度下 ,θ对ab平面上的铁磁态产生的谱峰的共振场位置几乎没有影响 :而在c轴方向上的铁磁 顺磁转变温度Tcc 以下 ,θ对c轴方向上的铁磁态产生的谱峰的共振场位置有着显著的影响 .其原因可能有两个 ,一是c轴和ab平面方向上的磁性质由于结构因素的影响而存在着差异 ,即各向异性 ;二是在c轴方向上可能存在强烈的退磁效应 ,而在ab平面方向上退磁效应可以忽略不计 .输运性质测量表明外加磁场明显地抑制了样品的电阻率 ρ ,样品表现出较强的磁电阻效应更多还原

【Abstract】 The electronic paramagnetic resonance spectra and transport properties of bilayered La\-\{1.4\}Sr\-\{1.6\}Mn\-2O\-7 epitaxial film have been studied. The resonance field positions of the EPR spectra which result from the ferromagnetic state in the ab plane have almost no relationship with the angle θ between the external magnetic field and the ab plane of the film at any temperature. But below T\+c\-c (the ferromagnetic paramagnetic phase transition temperature along the c axis of the film), those of the EPR spectra which are involved in the ferromagnetic state along the c axis are greatly influenced by changing θ . There are two reasons: one is that there are some differences between the magnetic properties along the c axis and those in the ab plane, i.e. anisotropy; the other reason is that the demagnetization may exist along the c axis, which does almost not exist in the ab plane. The measurement of the transport properties demonstrates that the resistivity ρ is apparently suppressed by an external magnetic field, showing the rather strong magnetoresistance effect.更多还原