The magnetic properties of thin-film multilayers [Fe/Py]/FeMn/Py are investigated as a function of temperature and thickness of the antiferromagnetic FeMn spacer using SQUID magnetometry. The observed behavior differs substantially for the structures with 6 nm and 15 nm FeMn spacers. While the 15 nm FeMn structure exhibits exchange pinning of both ferromagnetic layers in the entire measurement temperature interval from 5 to 300 K, the 6 nm FeMn structure becomes exchange de-pinned in the vicinity of room temperature. The depinned state is characterized by a single hysteresis loop centered at zero field and having enhanced magnetic coercivity. The observed properties are explained in terms of finite-size effects and possible ferromagnetic interlayer coupling through the thin antiferromagnetic spacer.

中文翻译：

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[Fe/Py]/FeMn/Py 多层膜的温度和厚度相关的静磁特性

使用 SQUID 磁力计研究了多层薄膜 [Fe/Py]/FeMn/Py 的磁性作为反铁磁 FeMn 间隔物的温度和厚度的函数。对于具有 6 nm 和 15 nm FeMn 间隔物的结构，观察到的行为有很大不同。虽然 15 nm FeMn 结构在 5 到 300 K 的整个测量温度区间内表现出两个铁磁层的交换钉扎，但 6 nm FeMn 结构在室温附近变得无交换钉扎。脱销状态的特征在于以零场为中心并具有增强的矫顽力的单个磁滞回线。观察到的特性是根据有限尺寸效应和可能通过薄反铁磁隔离物的铁磁层间耦合来解释的。