Supplementary Materials for
Antisite defects in La0.7Sr0.3MnO3 and La0.7Sr0.3FeO3
Meng Gu1,2, Zhiguo Wang3, Michael D. Biegalski4, Hans M. Christen4, Yayoi Takamura1 and
Nigel D. Browning1, 5, 6
1
Department of Chemical Engineering and Materials Science, University of California-Davis,
Davis, California, 95616
2
Present address: Environmental Molecular Sciences Laboratory, Pacific Northwest National
Laboratory, Richland WA 99354
3
Department of Applied Physics, University of Electronic Science and Technology of China,
Chengdu, 610054, P.R. China
4
Center for Nanophase Materials Science, Oak Ridge National Laboratory, Oak Ridge,
Tennessee, 37831; 5Department of Molecular and Cellular Biology, University of CaliforniaDavis, Davis, CA, 95616, 95616;
6
Present address: Fundamental & Computational Sciences Directorate, Pacific Northwest
National Laboratory, Richland WA 99354
This supplementary material section provides details regarding to Z-contrast imaging,
electron energy loss (EEL) spectroscopy, and the density functional theory (DFT) calculations in
this study.
The KrF laser (248 nm) was operated at 10 Hz with an energy density of ~ 1.5 J/cm 2. The
substrate was heated to 7700C and the chamber pressure was held at 200 mTorr O2. The growth
of these superlattices was monitored in-situ using reflection high energy electron diffraction.
After the deposition, the film was cooled to room temperature in 200 Torr of O2. The samples for
STEM were polished to electron transparency using the wedge polishing method using a Multiprep machine from Allied High Tech Products, Inc. A Fischione ion milling system was used for
low-voltage (2kV) Ar cleaning for about 30 minutes to remove the mechanically damaged
surface layer. The images shown in Fig. 1(a,b) and Fig. 2 were obtained using a probe
aberration-corrected JEM2100F STEM operating at 200 kV with a convergence angle of 18
mrad and collection semi-angle of around 110-300 mrad at UC Davis. The images in Fig. S2 and
EEL spectra were acquired using the TEAM 0.5 microscope operating at 80 kV to avoid beam
damage at the National Center for Electron Microscopy at Lawrence Berkeley National
Laboratory. The Z-contrast images acquired using TEAM 0.5 had a convergence angle of 29
mrad and collection semi-angle of 90-390 mrad and the EELS inner collection angle was 100
mrad.
The first-principles calculations are performed based on DFT using projector augmented
wave potentials (PAW)1. The exchange correlation is described in the generalized gradient
approximations (GGA)2 using the PW91 functional as implemented in the VASP code3. PAW
potentials with valence configurations of 5s25p65d16s2, 3p63d64s2, 3d64s1, and 2s22p4 are used to
describe the La, Fe, Mn and O atoms, respectively. Defect calculations are simulated with 240atom (4a0×4a0×3a0; a0 is the lattice constant of a cubic LaMnO3 (LMO) or LaFeO3 (LFO)
perovskite) supercell. A plane-wave expansion of the wave functions up to a kinetic-energy
cutoff of 400 eV has been employed and the Brillouin zone was sampled by a Monkhorst-Pack kpoint mesh of 2×2×2.
The defect formation energy of a native defect is simply the reaction energy to create the
defect from ideal matter. The formation energy is not a constant but depends on the growth or
annealing conditions4. The formation energy of a defect in charge state is defined as4,
E f [ X q ]  Etot [ X q ]  Etot [pefect ]   ni i  q( EF  EVBM )
(1)
i
where Etot [ X q ] is the total energy of a supercell containing a relaxed defect (vacancy or antisite)
with charge state q, Etot [pefect ] is the total energy of the supercell without defects. ni indicates
the number of atoms of type i atoms that have been added to (ni>0) or removed from (ni<0) the
supercell. EF is the Fermi level referenced to the valence band maximum (EVBM) in the bulk
materials.  i are the corresponding chemical potentials of these species.
The ranges of the chemical potentials  La ,  Mn ,  Fe and  O are defined by:
(i) the values that prevent the formation of pure metals (La, Fe, Mn) and O2 gas. In
thermodynamic equilibrium the component chemical potential cannot be higher than the
energy of bulk materials of this species. For example, if we tried to push the  La higher than
Bulk
 La
we would no longer be growing LaMnO3, but instead precipitating metal Mn:
Bulk
Bulk
Bulk
 La   La
;  Mn   Mn
;  Fe   Fe
; and  O   OO
2
(2)
(ii) the values that prevent the formation of binary oxides:
Bulk
Bulk
Bulk
, 2Fe  3O  Fe
, 2Mn  3O  Mn
2La  3O  La
2O3
2O3
2O3
(3)
(iii) the values that maintain a stable LMO or LFO compounds:
Bulk
Bulk
, La  Fe  3O  LaFeO
La  Mn  3O  LaMnO
3
3
(4)
These conditions are applied to the ternary LMO and LFO system and allow determining the
chemical potential from the various equilibrium conditions. Fig. 4(a) shows the phase diagram of
the ternary La-Mn-O (La-Fe-O) system, which is derived from the combination of the chemical
potentials of Mn (Fe), Mn2O3 (Fe2O3), La, La2O3, and O2. The vertices of the triangle correspond
to three dominant component chemical potentials and the compounds are placed on the edge
according to their stoichiometric proportion. Points A–E denoted the five possible chemicalpotential combinations and the intersections of these five points define the thermodynamically
equilibrium region of the ternary system under different chemical potentials. At points A and B,
the chemical potentials for O are similar to a strongly oxidation environment like those LMO
(LFO) sample grown in an O2 rich state. On the contrary, at point D the system is in a strongly
reducing environment. Under the assumption that LMO (LFO) is always stable, the atomic
chemical potentials for La, Mn (Fe), and O are constrained by the following equilibrium
equations, we take LMO as an example:
Bulk
Point A: 2Mn  3O  Mn
,  O   OO2
2O3
(5)
Bulk
Point B: 2La  3O  La
,  O   OO2
2O3
(6)
Bulk
Bulk
Point C: 2La  3O  La
,  La   La
2O3
(7)
Bulk
Bulk
Point D:  Mn   Mn
,  La   La
(8)
Bulk
Bulk
Point E: 2Mn  3O  Mn
,  Mn   Mn
2O3
(9)
The chemical potential of O was calculated from the total energy of O2 molecule, the bulk
materials La (FCC), α-Mn, Fe (FCC), and La2O3 (P-3m1), Mn2O3 (Pcab), and Fe2O3 (R-3c) are
used to calculate their chemical potential in the compound.
Fig.4(b) and (c) shows the formation energies of various defects along the vertices
(A→B→C→D→E) defined in Fig.4(a). It can be seen the defect formation energies show great
dependence on the chemical potentials. Under oxidation conditions, the vacancies of La, Mn and
Fe exhibit negative formation energy. The large negative energies suggest formations of cation
vacancies are thermodynamically favorable under O2-rich conditions. Formation of cation
vacancies (oxygen overstoichiometry) will persist until the cation vacancy concentration is high
enough that the cation vacancy interactions compensate for the negative cation vacancy
formation energy. In contrast, under reducing conditions the formation energies of V Fe, VMn, LaFe,
LaMn and VO show the lower formation energy, indicating that LaFe and LaMn antisites occur
easily under reducing condition companied with amount of oxygen and Mn (Fe) vacancies, and
in this case La will be overstoichiometry.
The EEL spectra shown in Fig. 3 are raw spectra without normalization. The EEL spectra were
background subtracted before the Mn/Fe L edge and overlaid together for comparison in Fig. 3.
The signal for Mn/Fe (B site species) in the defect region is lower than normal region, while the
signal of La (A site species) in the defect region is higher than the normal region. (The O K edge
spectra corresponding to these spectra are overlaid for comparison in Fig. S3.) The thickness
effect on the EEL signal can be excluded considering the fact that thickness variations will only
result in coherent changes in the core edges of Mn/Fe and La. Therefore, we conclude that the
EEL spectra provide important clues on the formation of these antisite defects.
Fig S1. Overall view Z-contrast (a) and bright field image (b) of the film and STO substrate
region. Note: the defect contours are circled in red in the bright field image and no such clustershaped defect contours are observed in the STO substrate region.
Fig S2 (a) Z-contrast image where some regions with enhanced contrast can be observed. (b)
Integrated Mn (Fe) L edge divided by O K edge intensity maps from the red rectangular region
shown in (a). (c) Integrated Mn (Fe) L edge divided by O K edge intensity line scans across the
whole film from the film surface to the interface marked by the white line in (a).
Fig S3. Raw O K edge comparison of the defect and normal regions at LSMO layer (a) and
LSFO layer (b); (c) plot of the normalized O K edges normalized to the middle peak of O K edge
at LSFO layer
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