arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 2008.08600cond-mat.mes-hall
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磁场中多铁性复合畴壁的动力学及其不稳定性

Dynamics of Composite Domain Walls in Multiferroics in Magnetic Field and Their Instability

Koji Kawahara, Hirokazu Tsunetsugu

摘要:

从理论上研究了磁场驱动下多铁性材料GdFeO $H$中复合畴壁的动力学行为。在低温下,Fe和Gd的两个反铁磁自旋与Gd离子位移相互作用,并与$c$耦合,数值模拟了相应的含时Ginzburg-Landau方程,其中磁场$H$与Fe自旋序参量耦合.我们系统地改变了$H$和$c$,计算了磁性DW和磁电DW在定态下的速度$v$和内部结构。对于两种DW,DW迁移率$v/H$随$H$增加而随$c$减少,但它们的特性在两者之间不同。我们还用微扰理论分析了磁电双折射波的光滑特性。另一个发现是在大H处的分裂不稳定性。当$c$大时,磁电DW分裂成一对磁性DW和电DW,而当$c$小时,磁性DW分裂。复合材料DW的内部结构随着$c$和$H$的增加而发生变形,不同序参量的调制在空间上发生分离。它们的相对距离随着接近分裂不稳定性而显著增大。

英文摘要:

We study theoretically the dynamics of composite domain walls (DW) in multiferroic material GdFeO${}_3$ driven by magnetic field $H$. Two antiferromagnetic orders of Fe and Gd spins interact Gd-ion displacement in this system with coupling $c$ at low temperatures, and we have numerically simulated the corresponding time-dependent Ginzburg-Landau equations in which magnetic field $H$ couples to Fe-spin order parameter. We vary $H$ and $c$ systematically and calculate velocity $v$ and inner structure in a stationary state for magnetic DW and magneto-electric DW. DW mobility $v/H$ increases with $H$ and decreases with $c$ for both DWs, but their characteristics differ between the two. We have also studied analytically the smooth characteristics of magneto-electric DW by perturbation theory. Another finding is a splitting instability at large H. A magneto-electric DW splits into a pair of magnetic DW and electric DW when $c$ is large, while a magnetic DW splits when $c$ is small. Internal structure of composite DW deforms with increasing $c$ and $H$, and modulations in different order parameters separate in space. Their relative distances show a noticeable enhancement with approaching the splitting instability.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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