Coherent tunnelling conductance in magnetic tunnel junctions of half-metallic full Heusler alloys with MgO barriers
Coherent tunnelling conductance in magnetic tunnel junctions of half-metallic full Heusler alloys with MgO barriers
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DOI：
10.1088/0953-8984/19/36/365228
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发表时间：
2007-09-12
影响因子：
2.7
通讯作者：
Shirai, Masafumi
中科院分区：
文献类型：
--
作者：
Miura, Yoshio;Uchida, Hirohisa;Shirai, Masafumi
基于密度泛函理论和Landauer公式，对MgO和半金属全Heusler合金Co_2MnSi组成的磁性隧道结（MTJ）进行了电子结构和输运计算.研究发现，由于对称性的降低，Co2 MnSi/MgO（001）界面处Co原子的态密度向高能侧移动，导致界面处的自旋极化降低.此外，我们还发现，由于Co_2MnSi的Delta（1）沟道的隧穿，多数自旋透射率作为平行于的面内波矢k的函数具有以k（平行于）=（0，0）为中心的宽峰，而Delta（5）沟道的透射率比Delta（1）沟道的透射率小三个数量级。这些结果表明，在具有Co2 MnSi和MgO势垒的MTJ中，如在Fe/MgO/Fe（001）MTJ和相关系统中，通过Delta（1）带的相干隧穿也占主导地位。
We have carried out electronic structure and transport calculations for magnetic tunnel junctions (MTJ) composed of MgO and a half-metallic full Heusler alloy Co2MnSi on the basis of the density functional theory and the Landauer formula. We find that the density of states of Co atoms at the Co2MnSi/MgO(001) interface shifts toward the higher energy side due to the reduced symmetry, leading to a reduction of the spin polarization at the interface. Furthermore, we show that the majority-spin transmittance as a function of the in-plane wavevector k parallel to has a broad peak centred at k(parallel to) = (0, 0) due to the tunnelling from the Delta(1) channel of Co2MnSi, while the transmittance from the Delta(5) channel is three orders of magnitude smaller than that of the Delta(1) channel. These results indicate that coherent tunnelling through the Delta(1) band is dominant also in an MTJ with Co2MnSi and an MgO barrier, like in Fe/MgO/Fe(001) MTJ and related systems.