Synthetic ferrimagnet nanowires with very low critical current density for coupled domain wall motion.
Synthetic ferrimagnet nanowires with very low critical current density for coupled domain wall motion.
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DOI：
10.1038/s41598-017-01748-7
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发表时间：
2017-05-09
影响因子：
4.6
通讯作者：
Marrows CH
中科院分区：
文献类型：
--
作者：
Lepadatu S;Saarikoski H;Beacham R;Benitez MJ;Moore TA;Burnell G;Sugimoto S;Yesudas D;Wheeler MC;Miguel J;Dhesi SS;McGrouther D;McVitie S;Tatara G;Marrows CH
铁磁纳米线中的畴壁是未来技术的潜在基石，例如赛道存储器，其中畴壁中编码的数据使用自旋极化电流传输。然而，高能效器件的发展受到了启动畴壁运动所需的高电流密度的阻碍。在这里，我们表明，一个显着的临界电流密度的减少，可以实现在CoFe/Ru/CoFe合成亚铁磁轨道的面内磁化耦合畴壁。层之间的反铁磁交换耦合导致简单的Néel壁结构，使用光电发射电子和洛伦兹透射电子显微镜成像，宽度仅为~100 nm。使用磁输运测量法测得的使这些壁运动的临界电流密度为1.0 × 1011 Am−2，几乎比铁磁耦合的对照样品低一个数量级。理论模型表明，这是由于非绝热驱动的各向异性耦合壁，一种机制，可用于设计有效的畴壁设备。
Domain walls in ferromagnetic nanowires are potential building-blocks of future technologies such as racetrack memories, in which data encoded in the domain walls are transported using spin-polarised currents. However, the development of energy-efficient devices has been hampered by the high current densities needed to initiate domain wall motion. We show here that a remarkable reduction in the critical current density can be achieved for in-plane magnetised coupled domain walls in CoFe/Ru/CoFe synthetic ferrimagnet tracks. The antiferromagnetic exchange coupling between the layers leads to simple Néel wall structures, imaged using photoemission electron and Lorentz transmission electron microscopy, with a width of only ~100 nm. The measured critical current density to set these walls in motion, detected using magnetotransport measurements, is 1.0 × 1011 Am−2, almost an order of magnitude lower than in a ferromagnetically coupled control sample. Theoretical modelling indicates that this is due to nonadiabatic driving of anisotropically coupled walls, a mechanism that can be used to design efficient domain-wall devices.