Extended x-ray absorption fine structure (EXAFS) has been used to measure the bond length in a 23 Å epitaxial Gd2O3 film grown on GaAs(001). The Gd–O bond length is determined to be 2.390±0.013 Å, which corresponds to a +0.063±0.013 Å increase or a +2.7%±0.6% bond-length strain relative to the bond length in a bulk Gd2O3 powder. Using a simple model for the strained film that matches the [001] and [−110] axes of Gd2O3 with the [110] and [1–10] axes of the GaAs(001) surface, the measured bond-length increase of the film determined by EXAFS agrees well with the perpendicular lattice distortion of the film determined by diffraction.

1.
M.
Hong
,
J.
Kwo
,
A. R.
Kortan
,
J. P.
Mannaerts
, and
A. M.
Sergent
,
Science
283
,
1897
(
1999
).
Google Scholar
 
2.
A. R.
Kortan
,
M.
Hong
,
J.
Kwo
,
J. P.
Mannaerts
, and
N.
Kopylov
,
Phys. Rev. B
60
,
10913
(
1999
).
Google Scholar
 
3.
The experimental error corresponds to the spread of bond lengths which doubles the residual chi-squared error while the coordination number is allowed to vary.
4.
The unstrained 2.327 Å bulk Gd–O bond length is the average bond length of the refined Gd2O3 structure of Refs. 5,6 7 using the lattice constant a=10.813 Å. The basic-structure bond length is ∛a(Gd2O3)/8=2.341 Å. As EXAFS measures the change in bond length of the film relative to the powder, the value Δr=+0.063±0.013 Å is model independent.
5.
L.
Pauling
and
M. D.
Shappell
,
Z. Kristallogr.
75
,
128
(
1930
).
Google Scholar
 
6.
M.
Marezio
,
Acta Crystallogr.
20
,
723
(
1966
).
Google Scholar
 
7.
G.
Gashurov
and
O. J.
Sovers
,
Acta Crystallogr., Sect. B: Struct. Crystallogr. Cryst. Chem.
26
,
938
(
1970
).
Google Scholar
 
8.
J. C.
Woicik
,
J. G.
Pellegrino
,
B.
Steiner
,
K. E.
Miyano
,
S. G.
Bompadre
,
L. B.
Sorensen
,
T.-L.
Lee
, and
S.
Khalid
,
Phys. Rev. Lett.
79
,
5026
(
1997
).
Google Scholar
 
9.
(Δr/r)avg=(ε[110]+ε[−110]+ε[001])/3=+2.9% and (Δr/r)EXAFS=+2.7%±0.6%.
10.
J. C.
Woicik
,
C. E.
Bouldin
,
K. E.
Miyano
, and
C. A.
King
,
Phys. Rev. B
55
,
15386
(
1997
).
Google Scholar
 
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