Effects of post-growth annealing on structural and compositional properties of the Co2Cr0.6Fe0.4Al surface and its relevance for the surface electron spin polarization
Effects of post-growth annealing on structural and compositional properties of the Co2Cr0.6Fe0.4Al surface and its relevance for the surface electron spin polarization
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DOI：
10.1088/0022-3727/42/8/084016
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发表时间：
2009-04-21
影响因子：
3.4
通讯作者：
Cinchetti, Mirko
中科院分区：
文献类型：
--
作者：
Wuestenberg, Jan-Peter;Fischer, Johannes;Cinchetti, Mirko
在这项研究中，我们研究了不同的Co2Cr0.6Fe0.4Al样品生长后退火的影响。我们发现强烈的变化，在退火过程中的几何表面结构，以及在元素的特定浓度。这些不可逆的变化与表面处的电子自旋极化（ESP）的特征变化密切相关：如Cinchetti等人（2007 J. Phys. D：Appl.Phys.40 1544）中所观察到的，铁缓冲样品在费米能级处显示出最大的自旋极化。由于预测的少数能隙导致少数载流子的态密度降低，后者保持为正，这对于高于400摄氏度的建议最低退火温度的所有样品都可以清楚地看到。高于该温度，我们观察到ESP中的特征下降，作为结构质量增加的标志。它出现在0.6 eV的结合能，并在实验和理论中看到的少数电子态密度的峰值一致。
In this study we investigate the influence of post-growth annealing on different Co2Cr0.6Fe0.4Al samples. We find strong changes in the geometric surface structure as well as in the element specific concentrations during the annealing process. These irreversible changes go in hand with characteristic changes in the electron spin polarization (ESP) at the surface: as observed in Cinchetti et al (2007 J. Phys. D: Appl. Phys. 40 1544), the iron buffered sample shows the largest spin polarization at the Fermi level. The latter remains positive as a consequence of the reduced density of states for the minority carriers due to the predicted minority gap, which can be clearly seen for all samples above the proposed minimum annealing temperature of 400 degrees C. Above this temperature we observe a characteristic dip in the ESP as a sign of increasing structure quality. It appears at 0.6 eV binding energy and is consistent with a peak in the minority electron density of states seen in both experiment and theory.