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采用直流溅射法在 ( 1 0 0 )LaAlO3 单晶基片上制备了La0 67Sr0 3 3 MnO3 +δ/Pr0 7Ca0 3 MnO3 +δ/La0 67Sr0 3 3 MnO3 +δ(简称为LPL) 3层膜 .用X射线粉末衍射法(XRD)研究了系列样品的摇摆曲线和衍射全图 ,结果表明所有的样品均为高度取向的外延膜 .SQUID磁强计的测量结果证实了 3层膜中磁耦合的存在 .用常规的四端引线法测量了LSMO、PCMO和LPL 3层膜的电阻 ,分析了logρ 1 /T曲线 .由此可以得出如下结论 :具有铁磁性的PCMO中间层在 3层膜中可能起到了内磁场的作用 ,使得LSMO膜的顺磁性被削弱 ,这个作用与外加磁场的作用一样 ,降低了 ρmax,增大了由金属到半导体的转变温度Tp;PCMO中间层还诱发了LSMO的能隙中的态密度的变化 .以上两个原因使得在零场中样品的电阻率和Tp 随着中间层PCMO的厚度变化而明显变化 .
La0 67Sr0 3 3 MnO3 + δ / Pr0 7Ca0 3 MnO3 + δ / La0 67Sr0 3 3 MnO3 + δ (abbreviated as LPL) was deposited on the (100) LaAlO3 single crystal substrate by DC sputtering. X-ray powder diffraction (XRD) analysis of the series of samples rocking curve and diffraction pattern, the results show that all the samples are highly oriented epitaxial film.SQUID magnetometer measurements confirmed the presence of magnetic coupling in the three-layer film The resistance of the LSMO, PCMO and LPL 3-layer films was measured by a conventional four-terminal lead method and the logρ 1 / T curve was analyzed, from which it can be concluded that the PCMO interlayer with ferromagnetism may be in 3-layer films Plays the role of the internal magnetic field, making paramagnetic LSMO film is weakened, the role of the magnetic field and the role of the same, reducing the pmax, increasing the transition temperature from metal to semiconductor Tp; PCMO intermediate layer also induced LSMO The above two reasons cause the resistivity and Tp of the sample to change obviously with the thickness of PCMO in the middle layer.