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Strain-induced high ferromagnetic transition temperature of MnAs epilayer grown on GaAs (110).

Xu P, Lu J, Chen L, Yan S, Meng H, Pan G, Zhao J - Nanoscale Res Lett (2011)

Bottom Line: Specular and grazing incidence X-ray diffractions are used to study the influence of different strain states of MnAs/GaAs (110) and MnAs/GaAs (001) on the first-order magnetostructural phase transition.It comes out that the first-order magnetostructural phase transition temperature Tt, at which the remnant magnetization becomes zero, is strongly affected by the strain constraint from different oriented GaAs substrates.Our results show an elevated Tt of 350 K for MnAs films grown on GaAs (110) surface, which is attributed to the effect of strain constraint from different directions.PACS: 68.35.Rh, 61.50.Ks, 81.15.Hi, 07.85.Qe.

View Article: PubMed Central - HTML - PubMed

Affiliation: State Key Laboratory for Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, P,O, Box 912, Beijing 100083, China. jhzhao@red.semi.ac.cn.

ABSTRACT
MnAs films are grown on GaAs surfaces by molecular beam epitaxy. Specular and grazing incidence X-ray diffractions are used to study the influence of different strain states of MnAs/GaAs (110) and MnAs/GaAs (001) on the first-order magnetostructural phase transition. It comes out that the first-order magnetostructural phase transition temperature Tt, at which the remnant magnetization becomes zero, is strongly affected by the strain constraint from different oriented GaAs substrates. Our results show an elevated Tt of 350 K for MnAs films grown on GaAs (110) surface, which is attributed to the effect of strain constraint from different directions.PACS: 68.35.Rh, 61.50.Ks, 81.15.Hi, 07.85.Qe.

No MeSH data available.


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HRTEM image of sample D (MnAs/GaAs (110)). The crystallographic directions of the epitaxial film were indicated with white arrows.
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Figure 3: HRTEM image of sample D (MnAs/GaAs (110)). The crystallographic directions of the epitaxial film were indicated with white arrows.

Mentions: Atomic force microscopy (AFM) and MFM images taken from the growth surface are shown in Figure 1. One can see from Figure 1 that there is no evident stripe pattern in AFM images. Generally, all the samples in this study are very thin, and the stripe height is roughly 1% of the film thickness. As shown in Figure 1, the magnetic domains are randomly distributed in MFM images for MnAs films grown on both GaAs (110) and GaAs (001). We also observed the cross-sectional MFM images for MnAs/GaAs (001) and MnAs/GaAs (110). Although we can see sharp interfaces between MnAs and GaAs from Figure 2a,b, we cannot see evident borders between ferromagnetic α-phase and paramagnetic β-phase, indicating that the two phases are mixing together. Our results are different from observations in a 200-nm MnAs film epitaxied on GaAs (001) presented in [24], in which ferromagnetic α-phase and paramagnetic β-phase are obviously separated. We assumed this phenomenon resulted from the too thin thickness of MnAs layer. Figure 3 shows the HRTEM image of sample D, MnAs/GaAs (110), from which we can observe that MnAs films have a well-ordered crystal orientation and a sharp interface between MnAs and GaAs. Judged from the chromatic aberration of MnAs and GaAs substrate, the thickness of the epitaxial MnAs film is 11 nm.


Strain-induced high ferromagnetic transition temperature of MnAs epilayer grown on GaAs (110).

Xu P, Lu J, Chen L, Yan S, Meng H, Pan G, Zhao J - Nanoscale Res Lett (2011)

HRTEM image of sample D (MnAs/GaAs (110)). The crystallographic directions of the epitaxial film were indicated with white arrows.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3211171&req=5

Figure 3: HRTEM image of sample D (MnAs/GaAs (110)). The crystallographic directions of the epitaxial film were indicated with white arrows.
Mentions: Atomic force microscopy (AFM) and MFM images taken from the growth surface are shown in Figure 1. One can see from Figure 1 that there is no evident stripe pattern in AFM images. Generally, all the samples in this study are very thin, and the stripe height is roughly 1% of the film thickness. As shown in Figure 1, the magnetic domains are randomly distributed in MFM images for MnAs films grown on both GaAs (110) and GaAs (001). We also observed the cross-sectional MFM images for MnAs/GaAs (001) and MnAs/GaAs (110). Although we can see sharp interfaces between MnAs and GaAs from Figure 2a,b, we cannot see evident borders between ferromagnetic α-phase and paramagnetic β-phase, indicating that the two phases are mixing together. Our results are different from observations in a 200-nm MnAs film epitaxied on GaAs (001) presented in [24], in which ferromagnetic α-phase and paramagnetic β-phase are obviously separated. We assumed this phenomenon resulted from the too thin thickness of MnAs layer. Figure 3 shows the HRTEM image of sample D, MnAs/GaAs (110), from which we can observe that MnAs films have a well-ordered crystal orientation and a sharp interface between MnAs and GaAs. Judged from the chromatic aberration of MnAs and GaAs substrate, the thickness of the epitaxial MnAs film is 11 nm.

Bottom Line: Specular and grazing incidence X-ray diffractions are used to study the influence of different strain states of MnAs/GaAs (110) and MnAs/GaAs (001) on the first-order magnetostructural phase transition.It comes out that the first-order magnetostructural phase transition temperature Tt, at which the remnant magnetization becomes zero, is strongly affected by the strain constraint from different oriented GaAs substrates.Our results show an elevated Tt of 350 K for MnAs films grown on GaAs (110) surface, which is attributed to the effect of strain constraint from different directions.PACS: 68.35.Rh, 61.50.Ks, 81.15.Hi, 07.85.Qe.

View Article: PubMed Central - HTML - PubMed

Affiliation: State Key Laboratory for Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, P,O, Box 912, Beijing 100083, China. jhzhao@red.semi.ac.cn.

ABSTRACT
MnAs films are grown on GaAs surfaces by molecular beam epitaxy. Specular and grazing incidence X-ray diffractions are used to study the influence of different strain states of MnAs/GaAs (110) and MnAs/GaAs (001) on the first-order magnetostructural phase transition. It comes out that the first-order magnetostructural phase transition temperature Tt, at which the remnant magnetization becomes zero, is strongly affected by the strain constraint from different oriented GaAs substrates. Our results show an elevated Tt of 350 K for MnAs films grown on GaAs (110) surface, which is attributed to the effect of strain constraint from different directions.PACS: 68.35.Rh, 61.50.Ks, 81.15.Hi, 07.85.Qe.

No MeSH data available.


Related in: MedlinePlus