Magnetization reversal of Co/Pt multilayers: Microscopic origin of high-field magnetic irreversibility - art. no. 224434
Magnetization reversal of Co/Pt multilayers: Microscopic origin of high-field magnetic irreversibility - art. no. 224434
复制标题
DOI：
10.1103/physrevb.70.224434
复制
发表时间：
2004-12-01
影响因子：
3.7
通讯作者：
Liu, K
中科院分区：
文献类型：
--
作者：
Davies, JE;Hellwig, O;Liu, K
我们研究了具有垂直磁各向异性的[Co(4 Angstrom)/Pt(7 A)](50)多层中的磁化反转，宏观上通过一阶反转曲线（FORC）技术，微观上通过透射X射线显微镜（TXRM）和共振X射线小角散射（SAS）。我们特别关注成核和饱和过程。磁化反转的开始由不可逆过程主导，该不可逆过程对应于源自早期成核的零维气泡域的一维条带域的雪崩式传播。在第二阶段，我们观察到主要可逆行为，其中整体域拓扑被保留。最后，另一个不可逆过程使样本达到负饱和，对应于域的收缩和湮灭。有趣的是，即使远远超出明显的主环路饱和场，FORC 图也表现出明显的不可逆切换，从而提供了真实（且明显更高）饱和场的直接测量。 TXRM 和 SAS 测量在微观层面上揭示，对于远高于表观饱和场的场，一些力矩可忽略不计的残余气泡域仍然存在。这些残余磁畴如果未被消灭，将显着改变随后的磁化反转。
We investigate the magnetization reversal in [Co(4 Angstrom)/Pt(7 A)](50) multilayers with perpendicular magnetic anisotropy both macroscopically by the first-order reversal curve (FORC) technique and microscopically by transmission x-ray microscopy (TXRM) and resonant x-ray small angle scattering (SAS). In particular, we focus on the nucleation and saturation processes. The onset of magnetization reversal is dominated by irreversible processes corresponding to the avalanchelike propagation of one-dimensional stripe domains that originate from earlier nucleated zero-dimensional bubble domains. In a second stage we observe mainly reversible behavior where the overall domain topology is preserved. Finally another irreversible process brings the sample to negative saturation, corresponding to the contraction and annihilation of domains. Interestingly, even well beyond the apparent major-loop saturation field, the FORC diagram exhibits pronounced irreversible switching and thus provides a direct measure of the true (and significantly higher) saturation field. TXRM and SAS measurements reveal on a microscopic level that some residual bubble domains with negligible moments still persist for fields well above the apparent saturation field. These residual domains, if unannihilated, significantly alter the subsequent magnetization reversal.