Morales R, Basaran Ali C, Villegas J E, Navas D, Soriano N, Mora B, Redondo C, Batlle X, Schuller Ivan K
Department of Chemical-Physics & BCMaterials, University of the Basque Country UPV/EHU, 48940 Leioa, Spain.
IKERBASQUE, Basque Foundation for Science, 48011 Bilbao, Spain.
Phys Rev Lett. 2015 Mar 6;114(9):097202. doi: 10.1103/PhysRevLett.114.097202. Epub 2015 Mar 5.
The exchange bias of antiferromagnetic-ferromagnetic (AFM-FM) bilayers is found to be strongly dependent on the ferromagnetic spin configuration. The widely accepted inverse proportionality of the exchange bias field with the ferromagnetic thickness is broken in FM layers thinner than the FM correlation length. Moreover, an anomalous thermal dependence of both exchange bias field and coercivity is also found. A model based on springlike domain walls parallel to the AFM-FM interface quantitatively accounts for the experimental results and, in particular, for the deviation from the inverse proportionality law. These results reveal the active role the ferromagnetic spin structure plays in AFM-FM hybrids which leads to a new paradigm of the exchange bias phenomenon.
反铁磁-铁磁（AFM-FM）双层膜的交换偏置被发现强烈依赖于铁磁自旋构型。在比铁磁关联长度更薄的铁磁层中，广泛接受的交换偏置场与铁磁层厚度的反比例关系被打破。此外，还发现了交换偏置场和矫顽力的异常热依赖性。一个基于平行于AFM-FM界面的弹簧状畴壁的模型定量地解释了实验结果，特别是与反比例定律的偏差。这些结果揭示了铁磁自旋结构在AFM-FM混合体系中所起的积极作用，这导致了交换偏置现象的一种新范式。
