Hajiri T, Yoshida T, Filianina M, Jaiswal S, Borie B, Asano H, Zabel H, Kläui M
Department of Materials Physics, Nagoya University, Nagoya 464-8603, Japan.
J Phys Condens Matter. 2018 Jan 10;30(1):015806. doi: 10.1088/1361-648X/aa9ba7. Epub 2017 Dec 5.
We report an unusual angular-dependent exchange bias effect in ferromagnet/antiferromagnet bilayers, where both ferromagnet and antiferromagnet are epitaxially grown. Numerical model calculations predict an approximately 45° period for the sign switching of the exchange-bias field, depending on the ratio between magnetocrystalline anisotropy and exchange-coupling constant. The switching of the sign is indicative of a competition between a fourfold magnetocrystalline anisotropy of the ferromagnet and a unidirectional anisotropy field of the exchange coupling. This predicted unusual angular-dependent exchange bias and its magnetization switching process are confirmed by measurements on fully epitaxial CoFeN/MnN bilayers by longitudinal and transverse magneto-optic Kerr effect magnetometry. These results provide a deeper understanding of the exchange coupling phenomena in fully epitaxial bilayers with tailored materials and open up a complex switching energy landscape engineering by anisotropies.
我们报道了铁磁体/反铁磁体双层膜中一种不寻常的角度依赖交换偏置效应，其中铁磁体和反铁磁体均为外延生长。数值模型计算预测，根据磁晶各向异性与交换耦合常数之间的比率，交换偏置场的符号切换周期约为45°。符号的切换表明铁磁体的四重磁晶各向异性与交换耦合的单向各向异性场之间存在竞争。通过纵向和横向磁光克尔效应磁力测量对完全外延的CoFeN/MnN双层膜进行测量，证实了这种预测的不寻常角度依赖交换偏置及其磁化切换过程。这些结果为深入理解具有定制材料的完全外延双层膜中的交换耦合现象提供了帮助，并通过各向异性开辟了复杂的开关能量景观工程。
