Direct evidence for a half-metallic ferromagnet
Direct evidence for a half-metallic ferromagnet
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DOI：
10.1038/33883
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发表时间：
1998-04-23
期刊：
影响因子：
64.8
通讯作者：
Venkatesan, T
中科院分区：
文献类型：
--
作者：
Park, JH;Vescovo, E;Venkatesan, T
半金属材料的特征是一种电子自旋表现出金属行为，而另一种电子自旋表现出绝缘行为。因此，在费米能级处态密度完全自旋极化，并且电导率由这些金属性的单自旋载流子主导。这种奇特的物理性质可能对与磁性和自旋电子学相关的技术应用产生重大影响。一些铁磁体系，例如赫斯勒化合物（1）和二氧化铬（2），理论上已被预测为半金属。然而，半金属体系尚未被直接证实，并且这些预测仍然存疑（3,4）。在此我们报道了对铁磁锰钙钛矿La0.7Sr0.3MnO3进行的自旋分辨光电子发射测量，其在远低于居里温度时直接展现出半金属性质。对于多数自旋，光电子发射光谱清晰地显示出金属性的费米截止，而对于少数自旋，它显示出一个绝缘能隙，在约0.6 eV结合能处谱权重消失。
Half-metallic materials are characterized by the coexistence of metallic behaviour for one electron spin and insulating behaviour for the other. Thus, the electronic density of states is completely spin polarized at the Fermi level, and the conductivity is dominated by these metallic single-spin charge carriers. This exotic physical property could have a significant effect on technological applications related to magnetism and spin electronics. Some ferromagnetic systems, such as Heusler compounds(1) and chromium dioxide(2), have been predicted theoretically to be half-metallic. However, a half-metallic system has not been demonstrated directly and the predictions are still in doubt(3,4). Here we report spin-resolved photoemission measurements of a ferromagnetic manganese perovskite, La0.7Sr0.3MnO3, which directly manifest the half-metallic nature well below the Curie temperature. For the majority spin, the photoemission spectrum clearly shows a metallic Fermi cut-off, whereas for the minority spin, it shows an insulating gap with disappearance of spectral weight at similar to 0.6 eV binding energy.