Magnetic domain memory cell and magnetoresistive thin films
Magnetic domain memory cell and magnetoresistive thin films
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DOI：
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发表时间：
2004
影响因子：
8.6
通讯作者：
L. Gan;R. Gomez
中科院分区：
文献类型：
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作者：
L. Gan;R. Gomez
最近出现了新一代电子设备，它们使用电子的自旋而不是电荷作为操纵信息的手段。这些所谓的“自旋电子”器件利用了磁性薄膜异质结构中的巨磁阻（GMR）等效应，并且已经在当今的高密度硬盘驱动器中商业化。GMR的发现带来的另一个潜在的重大经济影响预计来自非易失性磁性随机存取存储器（MRAM）。下一代器件的关键取决于GMR结构的磁阻灵敏度和稳定性的增强，以及改变一个或多个铁磁层的磁化的新方法的发明。在本论文中，我通过改进各种磁阻薄膜的制备工艺和开发一种利用电流脉冲诱导磁化开关的新型磁存储单元来解决这两个问题。在磁性多层膜的研究中，有三个先进的工艺问题得到了解决：（1）利用交换耦合来估算巨磁阻结构中超薄Cu膜中出现针孔的临界厚度和隧道磁阻（TMR）结构中Al_2O_3势垒的临界厚度;（ii）氧化铝和金属作为防止铁磁金属在空气中热氧化的屏障的作用;（iii）通过使用电化学沉积来制造薄膜和导线几何形状的纳米尺寸接触，评估实际器件中的弹道磁阻（BMR）效应。在电流脉冲诱导的磁性随机存取存储器的磁化开关的研究中，我们已经证明了畴壁运动图案化的铁磁薄膜的第一次和发展的选择性双稳态畴结构控制的电流脉冲。基于这些发现，我们建立并成功地实现了一个单字节的存储单元，它具有比传统的MRAM简单得多的结构。
A new generation of electronic devices that use the spin of the electron instead of its charge as a means to manipulate information has recently emerged. These so called “spintronic” devices exploit effects such as giant magneto-resistance (GMR) in magnetic thin-film heterostructures and are already commercialized in today's high-density hard disk drives. Another potential major economic impact from the discovery of GMR is anticipated to come from nonvolatile magnetic random access memory (MRAM). The keys to next generation devices depend upon the enhancement of magneto-resistive sensitivity and stability of GMR structures, as well as the invention of novel methods to change the magnetizations of one or more ferromagnetic layers. In this dissertation, I have addressed both aspects by improving fabrication processes in various magneto-resistive thin films and developing a novel magnetic memory cell utilizing current pulse induced magnetization switch. In the study of magnetic multilayer thin films, three advanced process issues have been addressed, these include: (i) the use of exchange coupling as a tool to estimate the critical thickness for the pinhole appearance in ultra-thin Cu films in GMR structures and Al2O3 barrier in tunneling magneto-resistance (TMR) structures; (ii) the role of aluminum oxides and metals as barriers against thermal oxidation of ferromagnetic metals in air; (iii) assessments of ballistic magneto-resistance (BMR) effects into practical devices by using electrochemical deposition to fabricate nanometer size contacts in both thin film and wire geometries. In the study of current pulse induced magnetization switch for MRAM, we have demonstrated domain wall motion in patterned ferromagnetic films for the first time and developed selective bi-stable domain configurations controlled by current pulses. Based on these discoveries, we built and successfully implemented a one-byte memory cell, which has far simpler structure than conventional MRAM.