First demonstration of three terminal MRAM devices with immunity to magnetic fields and 10 ns field free switching by electrical manipulation of exchange bias
First demonstration of three terminal MRAM devices with immunity to magnetic fields and 10 ns field free switching by electrical manipulation of exchange bias
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DOI：
10.1109/iedm19574.2021.9720599
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发表时间：
2021-12
期刊：
影响因子：
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通讯作者：
D. Zhu;Z. Guo;A. Du;D. Xiong;R. Xiao;W. Cai;K.W. Shi;S. Peng;K. Cao;S.Y. Lu;D. Zhu;G.F. Wang;H.X. Liu;Q. Leng;W. Zhao
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作者：
D. Zhu;Z. Guo;A. Du;D. Xiong;R. Xiao;W. Cai;K.W. Shi;S. Peng;K. Cao;S.Y. Lu;D. Zhu;G.F. Wang;H.X. Liu;Q. Leng;W. Zhao
我们首次展示了三端磁性随机存取存储器（MRAM）器件，其抗磁场强度高达2 T。这是通过采用IrMn/CoFeB复合自由层来实现的，其中面内磁化CoFeB层通过IrMn/CoFeB界面处的交换偏置（EB）而不是形状各向异性来稳定。对于数据写入，我们实现了EB的电场自由反转，从而实现了CoFeB层的开关，然后通过隧道磁阻（TMR）检测，比率超过100%。通过向Pt底电极注入电流，我们获得了10 ns的无场开关，目前受到我们的实验装置的限制。我们进一步报告了我们的设备的大耐久性，在$1\ \mu \mathrm{s}$写入脉冲> $1\times 10^{10}$，这要归功于三端设备结构。除了热辅助开关机制，宏观自旋模拟表明，自旋轨道力矩（SOT）可能是负责观察到的现象。我们提出的MRAM方案，以下简称EB-MRAM，解决了面内磁化SOT-MRAM的可扩展性挑战，并提供了一种新的无场数据写入策略，这是有希望开发高性能MRAM。
For the first time, we demonstrate three terminal magnetic random access memory (MRAM) devices with immunity to magnetic fields up to 2 T. This is accomplished by adopting an IrMn/CoFeB composite free layer, where the in-plane magnetized CoFeB layer is stabilized by the exchange bias (EB) at the IrMn/CoFeB interface, rather than shape anisotropy. For data writing, we realize electrical field free reversal of the EB, thus the switching of CoFeB layer, which is then detected by tunneling magnetoresistance (TMR) with ratios exceeding 100 %. Through injecting currents into the Pt bottom electrode, we have obtained 10 ns field free switching, limited currently by our experimental set-up. We further report a large endurance of our devices, > $1\times 10^{10}$ at $1\ \mu \mathrm{s}$ write pulses, thanks to the three terminal device structure. In addition to the thermal assisted switching mechanism, macrospin simulations indicate that spin orbit torque (SOT) could be responsible for the observed phenomena. Our proposed MRAM scheme, hereafter referred as EB-MRAM, addresses the scalability challenge of the in-plane magnetized SOT-MRAM and provides a new strategy for field free data writing, which is promising to develop high-performance MRAM.