Origin of the large voltage-controlled magnetic anisotropy in a Cr/Fe/MgO junction with an ultrathin Fe layer: First-principles investigation
Origin of the large voltage-controlled magnetic anisotropy in a Cr/Fe/MgO junction with an ultrathin Fe layer: First-principles investigation
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具有超薄 Fe 层的 Cr/Fe/MgO 结中大电压控制磁各向异性的起源：第一性原理研究
DOI：
10.1103/physrevb.101.144434
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发表时间：
2020-04
影响因子：
3.7
通讯作者：
Han X. F.
中科院分区：
文献类型：
--
作者：
Chen W. Z.;Jiang L. N.;Yan Z. R.;Zhu Y.;Wan C. H.;Han X. F.
压控磁各向异性（VCMA）由于其高效率的磁化开关而引起了广泛的关注。在具有Cr2 O3 Fe层的Cr/Fe/MgO结中实验观察到大的VCMA [Nozaki，Phys.Rev.Appl.5，044006（2016）]2331-701910.1103/PhysReved.5.044006，然而，其潜在机制仍不清楚。Cr/Fe/MgO/Fe磁性隧道结（MTJ）也因其量子阱（QW）状态和诱导的自旋相关共振隧穿而众所周知[Greullet，Phys. Rev. Lett. 99，187202（2007）] PRLTA00031 -900710.1103/PhysRevLett.99.187202。为了揭示大VCMA与量子阱态之间的关系，我们发展了一种结合二阶微扰理论的VCMA计算方法来研究它，我们发现VCMA系数达到fJ/Vm，与以前的三层Fe单层（ML）实验很好地匹配.系数振荡强烈，甚至改变其符号与Fe ML的数量的增加。通过与界面Fe原子费米面的比较，验证了VCMA的屏蔽电荷理论。有趣的是，对于铁磁层，该点上电子的量子阱态对奇（偶）磁层的VCMA贡献很大（没有）。此外，在界面Fe原子处的轨道分辨费米面的变化也对VCMA振荡起着重要作用，这以及QW态导致最大的VCMA为3-ML Fe。我们的研究结果加深了对Cr/Fe/MgO结中大VCMA的理解，这将有助于设计具有大VCMA的实用MTJ。
Voltage-controlled magnetic anisotropy (VCMA) has attracted broad interest due to its high efficiency in switching magnetization. Large VCMA was experimentally observed in Cr/Fe/MgO junction with ultrathin Fe layer [Nozaki , Phys. Rev. Appl. 5, 044006 (2016)]2331-701910.1103/PhysRevApplied.5.044006, whose underlying mechanism was still not clear however. The Cr/Fe/MgO/Fe magnetic tunnel junction (MTJ) is also well known for its quantum-well (QW) states and as-induced spin-dependent resonant tunneling [Greullet , Phys. Rev. Lett. 99, 187202 (2007)]PRLTAO0031-900710.1103/PhysRevLett.99.187202. Here, in order to uncover the relation between the large VCMA and the QW states, we developed a-resolved VCMA calculation method combined with the second-order perturbation theory to investigate it. We find the VCMA coefficient reachesfJ/V m matching well with the previous experiment with three monolayers (MLs) of Fe. The coefficient oscillates strongly and even changes its sign with increasing the number of Fe MLs. Comparing the-resolved VCMA with the Fermi surface of the interfacial Fe atom, the screening charges theory for VCMA was verified. ForMLs Fe, interestingly, the QW states ofelectron at thepoint provide large (no) contribution to the VCMA with odd (even) MLs. Moreover, the change of the orbital-resolved Fermi surface at the interfacial Fe atom also plays an important role on VCMA oscillation, which as well as the QW states results in the largest VCMA for 3-ML Fe. Our results deepen the understanding of the large VCMA in the Cr/Fe/MgO junction, which would be helpful to design a practical MTJ with large VCMA.
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影响因子：
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作者：
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通讯作者：
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