Domain wall asymmetries in Ni81Fe19/NiO: proof of variable anisotropies in exchange bias systems
Domain wall asymmetries in Ni81Fe19/NiO: proof of variable anisotropies in exchange bias systems
复制标题
Ni81Fe19/NiO 中的畴壁不对称性：交换偏压系统中可变各向异性的证明
DOI：
10.1088/1367-2630/11/8/083016
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发表时间：
2009
影响因子：
3.3
通讯作者：
R. Schäfer
中科院分区：
文献类型：
--
作者：
J. McCord;R. Schäfer
报道了Ni 81 Fe 19/NiO交换耦合膜由于铁磁/反铁磁界面耦合的改变而引起的磁畴壁内部结构的多重变化。根据反铁磁感应各向异性，观察到三种不同类型的畴壁。随着反铁磁层的增加，反涡旋间距减小的交叉结畴壁结构得到发展。对于交换偏置样品，磁化环的上升和下降分支出现畴壁结构的强不对称性。对于下降分支，对称的180° Néel壁发展，而在沿着上升环路分支的磁化反转期间，折叠的交叉结畴壁结构形成。这种新型的“锯齿形”交叉连接墙的特征在于交叉连接以不同的方式到达周围的域区域。壁的变化表明存在的双模耦合强度在交换耦合系统，这是根据交换偏置模型，假设钉扎和unpinned自旋在铁磁/反铁磁界面。
Multiple changes in the internal structure of magnetic domain walls due to alterations of the interfacial coupling across the ferromagnetic/antiferromagnetic interface are reported for Ni81Fe19/NiO exchange coupled films. Depending on the antiferromagnetically induced anisotropy, three different types of domain walls are observed. Cross-tie domain wall structures of decreased vortex to anti-vortex spacing develop with the addition of a thin antiferromagnetic layer. For exchange biased samples strong asymmetries in domain wall structure occur for the ascending and descending branch of the magnetization loop. For the descending branch a symmetric 180° Néel wall develops, whereas a folded cross-tie domain wall structure forms during magnetization reversal along the ascending loop branch. The novel type of ‘zig-zagged’ cross-tie wall is characterized by cross-ties reaching differently into the surrounding domain areas. The wall alterations indicate the existence of bi-modal coupling strengths in exchange coupled systems, which is in accordance with models of exchange bias that assume pinned and unpinned spins at the ferromagnetic/antiferromagnetic interface.