Perring T G, Adroja D T, Champion J D M, Aeppli G, Chaboussant G, Kimura T, Tokura Y, Manuel P
ISIS Neutron and Muon Source, STFC Rutherford Appleton Laboratory, Didcot, Oxon OX11 0QX, United Kingdom.
Physics Department, ETH CH-8093 Zurich, Switzerland.
J Phys Condens Matter. 2020 Jun 18;32(37). doi: 10.1088/1361-648X/ab88f1.
The compound LaSrMnO,= 0.30-0.40, consists of bilayers of ferromagnetic metallic MnOsheets that are separated by insulating layers. The materials show colossal magnetoresistance-a reduction in resistivity of up to two orders of magnitude in a field of 7 T-at their three-dimensional ordering temperatures,= 90-126 K, and are the layered analogues of the widely studied pseudo-cubic perovskite manganites, RAMnO(R = rare earth, A = Ca, Sr, Ba, Pb). Two distinct short-range orderings-antiferromagnetic fluctuations and correlated polarons, which are related to the magnetic and the lattice degrees of freedom respectively-have previously been discovered in LaSrMnO,= 0.40, and have each been qualitatively connected to the resistivity. Here, in a comprehensive study as a function of both temperature and magnetic field for the different hole-concentrations per Mn site of= 0.30 and 0.35, we show that antiferromagnetic fluctuations also appear at temperatures just above, and that the intensities of both the antiferromagnetic fluctuations and polaron correlations closely track the resistivity. In particular, for= 0.35 we show that there is a simple scaling relation between the intensities of the antiferromagnetic fluctuations and the in-plane resistivity that applies for the temperatures and magnetic fields used in the experiments. The results show that antiferromagnetic fluctuations are a common feature ofLaSrMnOwith ferromagnetic bilayers, and that there is a close connection between the antiferromagnetic fluctuations and polarons in these materials.
化合物LaSrMnO₃（x = 0.30 - 0.40）由铁磁金属MnO₂层组成，这些层被绝缘层隔开。该材料在其三维有序温度（T₃D = 90 - 126 K）下表现出巨磁电阻——在7 T磁场中电阻率降低高达两个数量级，并且是广泛研究的伪立方钙钛矿锰氧化物RAMnO₃（R = 稀土，A = Ca、Sr、Ba、Pb）的层状类似物。先前在LaSrMnO₃（x = 0.40）中发现了两种不同的短程有序——反铁磁涨落和相关极化子，它们分别与磁自由度和晶格自由度相关，并且各自都与电阻率有定性联系。在此，我们针对每个Mn位点不同空穴浓度x = 0.30和0.35，进行了一项作为温度和磁场函数的综合研究，结果表明反铁磁涨落在略高于该温度时也会出现，并且反铁磁涨落和极化子相关性的强度都紧密跟踪电阻率。特别是，对于x = 0.35，我们表明在反铁磁涨落强度与面内电阻率之间存在一个简单的标度关系，该关系适用于实验中使用的温度和磁场。结果表明，反铁磁涨落是具有铁磁双层的LaSrMnO₃的一个共同特征，并且这些材料中的反铁磁涨落与极化子之间存在紧密联系。
