Tailoring of the structural and magnetic properties of MnAs films grown on GaAs-strain and annealing effects
Tailoring of the structural and magnetic properties of MnAs films grown on GaAs-strain and annealing effects
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DOI：
10.1116/1.1978902
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发表时间：
2005-07-01
影响因子：
1.4
通讯作者：
Heun, S
中科院分区：
文献类型：
--
作者：
Däweritz, L;Herrmann, C;Heun, S
用分子束外延法在GaAs（001）和GaAs（111）B表面上生长了MnAs薄膜。利用X射线磁圆二色性光电子显微镜对MnAs/GaAs（001）和MnAs/GaAs（111）B薄膜的温度相关磁结构进行成像，并与超导量子干涉仪（SQUID）磁测量结果进行比较，研究了不同应变状态对铁磁α-MnAs和顺磁β-MnAs之间相变的影响，两个结构相和磁性相的空间分布。和转变温度。对于各向同性应变的MnAs/GaAs（111）B膜，相共存范围比各向异性应变的MnAs/GaAs（001）膜宽得多。饱和磁化强度随薄膜厚度的变化是不同外延取向薄膜的普遍性质，只要至少有一个MnAs（1120）方向在薄膜平面内。对于MnAs/GaAs（001）薄膜，这种变化与α和δ MnAs的条纹共存以及随薄膜厚度和温度变化的条纹内和条纹间磁相互作用有关。MnAs/GaAs（111）B的磁结构更为复杂，这是由于存在三个与α相等效的α相畴和一个由δ相共存的蜂窝状网络叠加而成的。MnAs/GaAs（001）薄膜的磁性能（饱和磁化强度、磁畴尺寸）可以通过生长后退火得到改善。在一定的膜厚度以上，这被膜的复杂磁结构抑制。(c)2005年美国真空学会。
MnAs films were deposited by molecular-beam epitaxy on GaAs(001) and GaAs(111)B surfaces. Imaging of the temperature-dependent magnetic structure by x-ray magnetic circular dichroism photoemission electron microscopy, and the comparison with magnetization measurements by superconducting quantum interference device (SQUID) magnetometry, is used to study the impact of the different strain state of MnAs/GaAs(001) and of MnAs/GaAs(111)B films on the phase transition between ferromagnetic alpha-MnAs and paramagnetic beta-MnAs, the spatial distribution of the two structural and magnetic phases,. and the transition temperature. For the isotropically strained MnAs/GaAs(111)B films, the phase coexistence range is much wider than for the anisotropically strained MnAs/GaAs(001) films. The characteristic change of the saturation magnetization with film thickness is found to be a universal property of films with different epitaxial orientation, if at least one MnAs (1120) direction is in the film plane. For MnAs/GaAs(001) films this variation is related to the striped coexistence of a and 8 MnAs and the changing intra- and inter-stripe magnetic interaction with film thickness and temperature. The magnetic structure of MnAs/GaAs(111)B is more complex due to the existence of three symmetry-equivalent a-phase domains superimposed by a honeycomb-like network of the coexisting 8 phase. The magnetic properties (saturation magnetization, domain size) of thin MnAs/GaAs(001) films can be improved by postgrowth annealing. Above a certain film thickness this is inhibited by the complex magnetic structure of the film. (c) 2005 American Vacuum Society.