Yttrium–iron–garnet (YIG) is attracting a lot of interest due to its applications in spintronic devices. Previous reports have shown that oxygen content is essential for tuning the structural and magnetic properties of YIG films. However, the effect was not remarkable due to the small change of oxygen content. It is interesting to explore the properties of YIG with greatly reduced oxygen contents, which has not been reported so far. Here we report on YIG thin films with heavily reduced oxygen contents via annealing with graphite, and their structural, magnetic, and electrical transport properties. Both the saturation magnetization and lattice parameter of the samples decrease with reduced oxygen content. Moreover, electrical resistivity can be reduced up to several orders of magnitude, so the low-temperature electrical transport properties of YIG thin films are studied for the first time. The electrical transport is dominated by the thermal activation behavior above 100 K. While below 100 K, it shows Mott-variable range hopping conduction for the 570 °C annealed sample and tunneling conduction for the other samples. This work indicates dramatic changes of properties for YIG with heavily reduced oxygen contents and paves the way for tuning other materials with oxygen content.

中文翻译：

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氧含量大大降低的 YIG 薄膜的结构、磁性和低温电传输特性

钇铁石榴石（YIG）因其在自旋电子器件中的应用而引起了很多兴趣。先前的报告表明，氧含量对于调整 YIG 薄膜的结构和磁性能至关重要。但由于氧含量变化不大，效果并不显着。探索氧含量大大降低的 YIG 的特性是很有趣的，到目前为止还没有报道。在这里，我们报告了通过与石墨退火而大幅降低氧含量的 YIG 薄膜及其结构、磁性和电传输特性。样品的饱和磁化强度和晶格参数都随着氧含量的降低而降低。此外，电阻率可以降低几个数量级，因此首次研究了YIG薄膜的低温电输运特性。电传输由高于 100 K 的热激活行为主导。当低于 100 K 时，它显示出 570 °C 退火样品的莫特可变范围跳跃传导和其他样品的隧道传导。这项工作表明，随着氧含量的大幅降低，YIG 的性能发生了巨大变化，并为调整其他含氧材料的材料铺平了道路。