论文标题
观察磁域和泡沫结构中的磁电sr $ _3 $ co $ _2 $ _2 $ fe $ _ {24} $ o $ $ _ {41} $
Observation of magnetic domain and bubble structures in magnetoelectric Sr$_3$Co$_2$Fe$_{24}$O$_{41}$
论文作者
论文摘要
使用Lorentz显微镜研究了Z型Hexaferrite SR $ _3 $ _2 $ _2 $ _2 $ _2 $ _2 $ _2 $ _2 $ _2 $ _2 $ _2 $ _2 $ _2 $ _ {41} $中的磁性域和气泡结构的磁性域和气泡结构。该六富晶表现出室温磁电效应，归因于其横向锥形结构（TC相）。加热后，TC相变成了铁磁相，在410至480 K（FM2相）之间，在六角形$ ab $平面中具有磁矩，并转变为另一个铁磁相，与$ c $轴平行于490和680 K（fm1相）之间的矩矩矩平相。因此，在这项研究中，观察到SR $ _3 $ _2 $ _2 $ _2 $ _ {24} $ o $ $ _ {41} $中的磁性域结构在温度下发生巨大变化。在TC相中，将样品从FM2到TC相冷却后观察到不规则的细磁域。在FM1相，与$ c $轴平行形成的带有明亮和深色对比的条纹磁性域墙。应用外部磁场后，条纹磁性域壁变成了磁性气泡。磁性气泡的拓扑取决于外部磁场（$ h $）方向和简易$ c $轴的角度。也就是说，具有拓扑数$ n $ = 1（I型）的磁性气泡是用$ h // c $创建的，而当磁场从C轴上倾斜5°时，创建了$ n $ = 0（II型）的磁性气泡。我们将Sr $ _3 $ CO $ _2 $ _2 $ fe $ _ {24} $ o $ $ $ _ {41} $的高磁结晶各向异性归因于FM1阶段的磁性气泡的出现。
The magnetic domain and bubble structures in the Z-type hexaferrite Sr$_3$Co$_2$Fe$_{24}$O$_{41}$ were investigated using Lorentz microscopy. This hexaferrite exhibits a room-temperature magnetoelectric effect that is attributed to its transverse conical spin structure (TC phase). Upon heating, the TC phase transforms into a ferrimagnetic phase with magnetic moments in the hexagonal $ab$ plane between 410 and 480 K (FM2 phase) and into another ferrimagnetic phase with moments parallel to the $c$ axis between 490 and 680 K (FM1 phase). Accordingly, in this study, the magnetic domain structures in Sr$_3$Co$_2$Fe$_{24}$O$_{41}$ were observed to change dramatically with temperature. In the TC phase, irregular fine magnetic domains were observed after cooling the specimen from the FM2 to TC phase. In the FM1 phase, striped magnetic domain walls with pairs of bright and dark contrast were formed parallel to the $c$ axis. Upon applying an external magnetic field, the striped magnetic domain walls transformed into magnetic bubbles. The topology of the magnetic bubbles was dependent on the angle between the external magnetic field ($H$) direction and the easy $c$ axis. Namely, magnetic bubbles with the topological number $N$ = 1 (type I) were created for $H//c$, whereas magnetic bubbles with $N$ = 0 (type II) were created when the magnetic field was tilted from the c axis by 5°. We attribute the high magnetocrystalline anisotropy of Sr$_3$Co$_2$Fe$_{24}$O$_{41}$ to the emergence of magnetic bubbles in the FM1 phase.
