Dept. of Physics, University of California, Davis, California 95616, USA.
NIST Center for Neutron Research, Gaithersburg, Maryland 20899, USA.
Sci Rep. 2016 Sep 8;6:32842. doi: 10.1038/srep32842.
Magnetic interactions in magnetic nanostructures are critical to nanomagnetic and spintronic explorations. Here we demonstrate an extremely sensitive magnetic yoking effect and tunable interactions in FePt based hard/soft bilayers mediated by the soft layer. Below the exchange length, a thin soft layer strongly exchange couples to the perpendicular moments of the hard layer; above the exchange length, just a few nanometers thicker, the soft layer moments turn in-plane and act to yoke the dipolar fields from the adjacent hard layer perpendicular domains. The evolution from exchange to dipolar-dominated interactions is experimentally captured by first-order reversal curves, the ΔM method, and polarized neutron reflectometry, and confirmed by micromagnetic simulations. These findings demonstrate an effective yoking approach to design and control magnetic interactions in wide varieties of magnetic nanostructures and devices.
磁性纳米结构中的磁相互作用对于纳米磁性和自旋电子学的探索至关重要。在这里，我们通过软层证明了基于 FePt 的硬/软双层中极其灵敏的磁轭效应和可调相互作用。在交换长度以下，软层强烈地与硬层的垂直磁矩交换耦合；在交换长度以上，仅几纳米厚，软层磁矩变为平面内，并作用于相邻硬层垂直畴的偶极场的轭。通过一级反转曲线、ΔM 方法和极化中子反射谱实验捕捉到从交换到偶极子主导相互作用的演化，并通过微磁模拟得到证实。这些发现展示了一种有效的轭合方法，可以设计和控制各种磁性纳米结构和器件中的磁相互作用。
