Camarero Julio, Sort Jordi, Hoffmann Axel, García-Martín Jose Miguel, Dieny Bernard, Miranda Rodolfo, Nogués Josep
Departamento de Física de la Materia Condensada and Instituto Nicolás Cabrera, Universidad Autónoma de Madrid, 28049 Madrid, Spain.
Phys Rev Lett. 2005 Jul 29;95(5):057204. doi: 10.1103/PhysRevLett.95.057204. Epub 2005 Jul 27.
The magnetization reversal in exchange-biased ferromagnetic-antiferromagnetic (FM-AFM) bilayers is investigated. Different reversal pathways on each branch of the hysteresis loop, i.e., asymmetry, are obtained both experimentally and theoretically when the magnetic field is applied at certain angles from the anisotropy direction. The range of angles and the magnitude of this asymmetry are determined by the ratio between the FM anisotropy and the interfacial FM-AFM exchange anisotropy. The occurrence of asymmetry is linked with the appearance of irreversibility, i.e., finite coercivity, as well as with the maximum of exchange bias, increasing for larger anisotropy ratios. Our results indicate that asymmetric hysteresis loops are intrinsic to exchange-biased systems and the competition between anisotropies determines the asymmetric behavior of the magnetization reversal.
研究了交换偏置铁磁 - 反铁磁（FM - AFM）双层膜中的磁化反转。当磁场从各向异性方向以特定角度施加时，通过实验和理论都得到了磁滞回线每个分支上不同的反转路径，即不对称性。角度范围和这种不对称性的大小由铁磁各向异性与界面铁磁 - 反铁磁交换各向异性之间的比率决定。不对称性的出现与不可逆性的出现相关，即有限矫顽力，以及与交换偏置的最大值相关，对于更大的各向异性比率，交换偏置最大值会增加。我们的结果表明，不对称磁滞回线是交换偏置系统所固有的，各向异性之间的竞争决定了磁化反转的不对称行为。
