Raman spectroscopy of<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow><mml:mi mathvariant="normal">CaMnO</mml:mi></mml:mrow><mml:mrow><mml:mn>3</mml:mn></mml:mrow></mml:msub></mml:mrow><mml:mo>:</mml:mo></mml:math>Mode assignment and relationship between Raman line intensities and structural distortions

Abrashev, M. V.; Bäckström, Joakim; Börjesson, Lars; Popov, V. N.; Chakalov, R. A.; Kolev, Nikolay Ivanov; Meng, R.L.; Iliev, M. N.

doi:10.1103/physrevb.65.184301

Cited by 128 publications

(96 citation statements)

References 19 publications

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“…The relative intensity of this disorder-induced Raman band may serve as a good indication of the oxygen deficit in LCMO 38 . In other articles 37,40,41,42 , these authors believe this band from the JT distortion of M nO 6 octahedra. Therefore, it is necessary to study the origin of the 600 cm −1 mode.…”

Section: Resultsmentioning

confidence: 99%

Raman spectra in epitaxial thin films ofLa1−xCaxMnO3(
Xiong
¹
,
Chen
²
,
Wang
³

et al. 2004
Phys. Rev. B
50
2
23
2
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Raman spectra of LCMO films grown on LAO (001), STO (001), and MgO (001) substrates were studied at different temperatures. The effect of temperature, doping level and strain on Raman spectra are discussed in detail. With decreasing temperature, the changes of Raman spectra are correlated with the disorder-order transition, shuch as: paramagnetism to ferromagnetism, and chargeordering. The strain induced by lattice-substrate mismatch affects the Raman spectra strongly. The mode induced by disorder of oxygen defects is apparently observed in La0.67Ca0.33M nO3 film on STO due to the larger tensile strain. While this mode can not be seen in the Raman spectra for the films on LAO and MgO. A strong unsigned mode at about 690 cm −1 is observed in all films except for La0.67Ca0.33M nO3 film on LAO, which is not observed in bulk sample easily. It suggests that the mode is closely related to the strain.

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Section: Resultsmentioning

confidence: 99%

Raman spectra in epitaxial thin films ofLa1−xCaxMnO3(
Xiong
¹
,
Chen
²
,
Wang
³

et al. 2004
Phys. Rev. B
50
2
23
2
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“…rotations of BO 6 octahedra around the cubic [001] c and [110] c axes, Jahn-Teller distortion, and La/Sr shift from its position in the ideal perovskite lattice. Analysis of literature data [14][15][16] implies that Raman spectra of La 1-x Sr x Ga 1-y Mn y O 3 crystals of Pbnm structure will be dominated by the modes activated by [110] c rotation and Jahn-Teller distortions.…”

Section: Resultsmentioning

confidence: 99%

Perovskite La1−x Sr x Ga1−y Mn y O3 solid solution crystals: Raman spectroscopy characterization

Runka

Berkowski

2012

J Mater Sci

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The first-order orthorhombic-rhombohedral phase transition of La 1-x Sr x Ga 1-y Mn y O 3 (LSGMn) crystals is studied by Raman spectroscopy. An increase in Mn content causes significant changes in Raman spectra, especially in the high-wavenumber spectral range. The Raman spectrum of La 1-x Sr x Ga 1-y Mn y O 3 compound with x = y = 0.02 is dominated by MnO 6 internal vibrations. Moreover, a change in the spectrum of this crystal is observed when the 785-nm excitation line is used. Essential reduction in the number of Raman modes during the phase transition is experimentally observed. The temperature of the phase transition decreases with increasing Sr and Mn contents, at the rate of about 20 K/at%.

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“…The isostructural orthorhombic Pnma compounds have close lattice parameters as well as close values of three of the four structural distortions, as defined in Ref. 4. The only difference is the presence of the JT distortion in Mn 3+ O 6 octahedra, leading to theirs strong deformation, whereas the Cr 3+ O 6 (Cr 3+ is not a JT ion) octahedra are symmetric with nearly equal Cr-O bonds.…”

mentioning

confidence: 92%

“…In manganites the JT effect results in presence of two pairs of Mn-O bonds of significantly different length and strongly deformed MnO 6 octahedra. For this reason, to explain the relationship between the intensity of the Raman lines and the structural distortions in orthorhombic manganites, a structural model accounting for four distortions (the two rotations from the Glazer model, the additional JT distortion and the so called A-shift) was proposed 4 . Within the framework of the latter model, it can be concluded that the intensities of 20 out of the all 24 Raman-active modes in the GdFeO 3 -type structure are connected with only one of the above mentioned distortions and the change of the intensities reflects the change of the structural distortions.…”

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confidence: 99%

Comparative Raman study of isostructural YCrO3and YMnO3: Effects of structural distortions and twinning

et al. 2011

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Polarized Raman spectra of isostructural orthorhombic YCrO 3 and YMnO 3 single crystals were collected at same conditions using different laser excitation in the visible range. The symmetry of the observed lines was determined and they were assigned to definite atomic vibrations based on lattice dynamical calculations. The frequencies of the lines of the same origin in both compounds are close, however, their intensities differ significantly. While the different intensity of the modes, activated by the Jahn-Teller distortion, can be explained by the different magnitude of this distortion in the two compounds, the cause of the reduced intensity of other lines in low frequency region in the Raman spectra of YMnO 3 is likely due to the fine twinning of the crystal. INTRODUCTIONThe interest in the transition-metal perovskite-like oxides ABO 3 continues for decades because of many attractive phenomena observed in these compounds. Among them are structural second-order phase transitions, high-T c superconductivity, colossal magnetoresistance, charge-and orbital-ordering, complex magnetic properties, etc. As a rule the structural, electrical and magnetic properties of these compounds are strongly correlated. They can be tuned through the change of the mismatch of the A-O and B-O bond lengths, expressed by the tolerance factor t = (R A + R O )/ √ 2(R B + R O ), where R O , R A and R B are the ionic radii of the oxygen and atoms in the A-and B-positions, respectively. Depending on the value of t, most of these compounds crystallize in superstructures of the ideal cubic perovskite (space group Pm3m) with R3c or Pnma symmetry. Using the model of Glazer 1 , treating the BO 6 octahedra as rigid ones, the superstructures can be obtained from the ideal cubic perovskite through some tilts (rotations) of the octahedra around the main crystallographic directions. In the Glazer's notations, the rhombohedral R3c structure is of (a − a − a − ) type and the orthorhombic Pnma structure is of (a − b + a − ) type.Raman spectroscopy is a powerful experimental technique for study of perovskite-like oxides. Due to the fact that there are no Raman-active modes in the ideal cubic perovskite, all observed lines in the one-phonon region of the Raman spectra of the real perovskites have to be connected to some deviations of the real structure from the ideal one. For example, as shown in the pioneering work of Scott 2 , one of the Raman-active modes in the rare-earth aluminates of R3c structure consists in a rigid octahedral tilt around [111] direction. This mode can be considered as a "soft mode" and its frequency goes to zero as the temperature approaches the critical temperature of the structural second-order phase transition. Iliev et al. 3 have shown that in the case of rare-earth manganites with orthorhombic Pnma structure, two of the observed lines in the Raman spectra originate from modes with a shape of the two static octahedral tilts, existing in the structure. Although that these compounds do not undergo second order transition to...

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Raman spectroscopy ofCaMnO3:Mode assignment and relationship between Raman line intensities and structural distortions

Cited by 128 publications

References 19 publications

Raman spectra in epitaxial thin films ofLa1−xCaxMnO3(
Xiong
¹
,
Chen
²
,
Wang
³

et al. 2004
Phys. Rev. B
50
2
23
2
View full text Add to dashboard Cite

Raman spectra in epitaxial thin films ofLa1−xCaxMnO3(
Xiong
¹
,
Chen
²
,
Wang
³

et al. 2004
Phys. Rev. B
50
2
23
2
View full text Add to dashboard Cite

Perovskite La1−x Sr x Ga1−y Mn y O3 solid solution crystals: Raman spectroscopy characterization

Comparative Raman study of isostructural YCrO3and YMnO3: Effects of structural distortions and twinning

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Raman spectroscopy ofCaMnO3:Mode assignment and relationship between Raman line intensities and structural distortions

Cited by 128 publications

References 19 publications

Raman spectra in epitaxial thin films ofLa1−xCaxMnO3(Xiong1, Chen2, Wang3 et al. 2004Phys. Rev. B502232View full textAdd to dashboardCite

Raman spectra in epitaxial thin films ofLa1−xCaxMnO3(Xiong1, Chen2, Wang3 et al. 2004Phys. Rev. B502232View full textAdd to dashboardCite

Perovskite La1−x Sr x Ga1−y Mn y O3 solid solution crystals: Raman spectroscopy characterization

Comparative Raman study of isostructural YCrO3and YMnO3: Effects of structural distortions and twinning

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Raman spectra in epitaxial thin films ofLa1−xCaxMnO3(
Xiong
¹
,
Chen
²
,
Wang
³

et al. 2004
Phys. Rev. B
50
2
23
2
View full text Add to dashboard Cite

Raman spectra in epitaxial thin films ofLa1−xCaxMnO3(
Xiong
¹
,
Chen
²
,
Wang
³

et al. 2004
Phys. Rev. B
50
2
23
2
View full text Add to dashboard Cite