We study the magnetic properties of epitaxial double-wedge CoO/Fe bilayers grown on MgO(001). We present a comprehensive set of data derived from the hysteresis loops measured as a function of temperature in a wide range of CoO and Fe thicknesses using Kerr microscopy imaging. We focus on relatively high temperatures and CoO layers with small thicknesses to address the onset of the exchange bias. We identify a characteristic CoO thickness of 30–40 Å, above which the films can be considered bulklike. However, a considerable exchange bias is still observed even for CoO films as thin as 12 Å if the temperature is sufficiently low. From the results of the x-ray photoelectron spectroscopy measurements, we deduce the presence of an interfacial iron oxide layer of mixed stoichiometry and a uniform composition of the CoO layer along the CoO wedge.

中文翻译：

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外延CoO / Fe（001）双层的磁性：交换偏压的发作与下层厚度和温度的关系

我们研究了在MgO（001）上生长的外延双楔CoO / Fe双层的磁性。我们提供了一组综合数据，这些数据是根据使用Kerr显微镜成像在很宽的CoO和Fe厚度范围内随温度变化测得的磁滞回线得出的。我们专注于相对较高的温度和厚度较小的CoO层，以解决交换偏压的开始。我们确定了特征性的CoO厚度为30–40Å，在该厚度以上，可以认为这些薄膜是块状的。但是，如果温度足够低，即使对于厚度仅为12的CoO膜，仍然观察到相当大的交换偏压。根据X射线光电子能谱测量的结果，我们推断出混合化学计量比的界面氧化铁层和沿着CoO楔的CoO层组成均匀。