Photon Factory Activity Report 2005 #23 Part B (2006)
Materials Science

3A/2005G127

Zn-Kα X-ray fluorescence holography ofdiluted magnetic semiconductor Zn0.4Mn0.6Te
Naohisa HAPPO*1, Shinya HOSOKAWA2, Makoto FUJIWARA1, Toru OZAKI2,Kenju HORII1, Kouichi HAYASHI3
1
Dept. of Info. Eng., Fac. of Info. Sci., Hiroshima City Univ., Hiroshima731-3194, Japan
2
Center for Mat. Res. using 3rd-Gen. SR Fac., Hiroshima Inst. of Tech., Hiroshima 731-5193, Japan
3IMR, Tohoku Univ., Sendai 980-8577, JapanIntroduction
From an X-ray diffraction [1], the lattice constant of
diluted magnetic semiconductor Zn1-xMnxTe linearlychanges with varying x (Vegard’s law), while an XAFS
results [2] showed almost unchanged Mn-Te and Zn-Tebond lengths (Pauling’s rule). This discrepancy led to aquestion of how the large MnTe4 tetrahedra can besqueezed into the small ZnTe4 lattice. X-ray fluorescenceholography (XFH) is a new technique that allows one tovisualize a three-dimensional (3D) local structure arounda specific element [3]. Recently, we have measured MnKα XFH of Zn0.4Mn0.6Te to obtain the local structurearound the Mn atoms [4]. From this experiment, imagesof Te sublattice were clearly seen, while the secondnearest-neighbor Zn or Mn atoms were barely visible. Itis, however, unclear whether the small scattering crosssections of Zn and Mn atoms or a highly distorted cation
sublattice causes such an experimental result. In this ZnKα XFH study, we have attempted to obtain a local
atomic image of Zn0.4Mn0.6Te around the Zn atoms, andsolve the above question.
ExperimentThe experimental setup is shown in Fig. 1. The Zn-Kα
XFH data were recorded at nine incident X-ray energiesof 11-15 keV in steps of 0.5 keV by rotating two axes (0°≤ φ ≤ 360° in steps of 0.5°, 0° ≤ θ ≤ 70° in steps of 1°) ofa single-crystal sample. The fluorescent X-rays werecollected using an avalanche photodiode detector with acylindrical graphite energy-analyzer at RT. The
Zn0.4Mn0.6Te sample was grown by a Bridgeman method,
and the incident X-rays were irradiated onto its (110)surface. From hologram patterns obtained with different
incident X-ray energies, a 3D atomic configuration image
was constructed using Barton’s algorithm [5].
Results and Discussion
The obtained atomic image of Zn0.4Mn0.6Te is depicted
in Fig. 2, for the (110) plane around the Zn atoms. The
green cross at the center of figure indicates the position of
the central Zn atom, and the red and black colors
represent the positions of neighboring atoms. The firstand third-nearest-neighbor Te atoms are clearlyvisualized. However, the second-nearest-neighbor Zn orMn atoms are barely visible in this image. Thus, it wasfound that Te sublattice is rigid and the cation sublattice132

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Fig. 1. The XFH experimental setup.

Fig. 2. The atomic image for the (110) planeof Zn0.4Mn0.6Te.
is highly distorted, which contradicts a structural model
for a similar diluted magnetic semiconductor Cd1-xMnxTeby Balzarotti et al. [6].
References[1] D. R. Yorder-Short et al., J. Appl. Phys. 58, 4056
(1985).
[2] N. Happo et al., J. Phys.: Condens. Matter 8, 4315
(1996).
[3] K. Hayashi et al., Phys. Rev. B 63, 041201 (2000).
[4] S. Hosokawa et al., Jpn. J. Appl. Phys. 44, 1011
(2005).
[5] J. J. Barton, Phys. Rev. Lett. 67, 3106 (1991).
[6] A. Balzarotti et al., Phys. Rev. B 30, 2295 (1984).
* happo@ce.hiorshima-cu.ac.jp