Raman and optical spectroscopic studies of small-to-large polaron crossover in the perovskite manganese oxides

Yoon, Seong Kuk; Liu, Hsiang Lin; Schollerer, Guido; Cooper, S. L.; Han, Peng; Payne, David A.; Cheong, S. W.; Fisk, Z.

doi:10.1103/physrevb.58.2795

Cited by 191 publications

(166 citation statements)

References 32 publications

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“…As shown in the Fig.2b, the intensities of ω 2 and ω 3 , increase with decreasing temperature compared with ω 1 . It is due to the change from smallpolaron-dominated transport in the paramagnetic (PM) phase to large-polaron (metallic) transport in the FM phase 48 . No obvious change in ω 4 is observed when the sample enters FM state.…”

Section: A Effect Of Temperaturementioning

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: A Effect Of Temperaturementioning

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
View full text Add to dashboard Cite

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“…10,21,22 This procedure provides an excellent description of all the measured spectra as shown in Fig. 2(a).…”

mentioning

confidence: 99%

Raman spectroscopy study of the interface structure in (CaCuO₂)_n/(SrTiO₃)_m superlattices

Castro¹,

Caramazza²,

Innocenti³

et al. 2013

Appl. Phys. Lett.

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Raman spectra of CaCuO 2 /SrTiO 3 superlattices show clear spectroscopic marker of two structures formed in CaCuO 2 at the interface with SrTiO 3 . For non-superconducting superlattices, grown in low oxidizing atmosphere, the 425 cm -1 frequency of oxygen vibration in CuO 2 planes is the same as for CCO films with infinite layer structure (planar Cu-O coordination). For superconducting superlattices grown in highly oxidizing atmosphere, a 60 cm -1 frequency shift to lower energy occurs. This is ascribed to a change from planar to pyramidal Cu-O coordination because of oxygen incorporation at the interface. Raman spectroscopy proves to be a powerful tool for interface structure investigation. Superconductivity indeed does appear only if the superlattices are grown under strongly oxidizing conditions, due to extra oxygen ions entering at the interface. 4,5,6 The larger the number of these oxygen ions is, the higher the hole doping of the CCO block and the T c are (a maximum T c 40 K has been obtained). 4 Excess oxygen ions occupy the apical position for the Cu ions of the CuO 2 planes close to the interface. 4,5,6 Therefore, different structures are present in the CCO layers close to the boundaries with SrTiO 3 and in those ones far from them. Indeed, the latter should retain their IL structure, with purely planar Cu-O coordination, whereas pyramidal Cu-O coordination can occur in the former. Recently, the occurrence of similar structural conditions has been also foreseen in films of IL system ACuO 2 (A = Ca, Sr, Ba) in a theoretical paper by Zhong et al. 7 and experimentally proven in the case of SrCuO 2 /SrTiO 3 superlattices. 8 Zhong et al. 7 found that, in order to reduce the electrostatic instability, naturally present in these highly polar systems, the structure changes, below a critical ACuO 2 thickness, from the CuO 2 planar (IL) to a chain structure by a tilting of the 3 CuO 2 planes. This transition is obtained by moving oxygen atoms from the CuO 2 planes to the Ca planes, thus leading to the presence of apical oxygen.Raman spectroscopy demonstrated to be a powerful tool to investigate layered structures 9,10 and to provide a careful characterization of film samples. 11 In particular, in cuprates with IL structure, the effects of the hole doping of CuO 2 planes, obtained by either introduction of excess oxygen atoms 12 or excitation through the charge transfer gap, 13 has

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“…However, the difficulty of this interpretation is that the temperature dependence of the spectral weight of the component is not consistent with the expected behavior of polarons. The peak strength should increase with decreasing temperature for polaronic absorption [20], but in the present compound, the peak spectral weight slightly decreases with decreasing temperature. An alternative explanation is that this electronic band also originates from an interband transition.…”

mentioning

confidence: 99%

Optical properties ofMgCNi3in the normal state

et al. 2005

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We present the optical reflectance and conductivity spectra for non-oxide antiperovskite superconductor M gCN i3 at different temperatures. The reflectance drops gradually over a large energy scale up to 33,000 cm −1 , with the presence of several wiggles. The reflectance has slight temperature dependence at low frequency but becomes temperature independent at high frequency. The optical conductivity shows a Drude response at low frequencies and four broad absorption features in the frequency range from 600 cm −1 to 33,000 cm −1 . We illustrate that those features can be well understood from the intra-and interband transitions between different components of Ni 3d bands which are hybridized with C 2p bands. There is a good agreement between our experimental data and the first-principle band structure calculations. The discovery of non-oxide superconductor M gCN i 3 has attracted much attention due to the coexistence of ferromagnetic element N i and superconductivity [1]. M gCN i 3 has the cubic antiperovskite lattice structure with space group P m3m, in which eight M g atoms occupy the cubic corners, while six Ni atoms are at the face-center positions and one C atom is inserted into the body-center position. The lattice parameter a is 3.81Å , and the specific heat measurements [5] show that M gCN i 3 is a conventional superconductor. But band calculations indicate that the N i 3d electrons dominate the density of the states (DOS) near the Fermi level E F [6,7,8,9]. Then, the N i 3d electrons are usually considered to take part in the superconducting pairing in M gCN i 3 . In such a case, an s-wave pairing is unexpected because of the existence of localized moment of Ni atom which will break the s-wave superconducting pairing.The relationship between the electronic states of N i and the superconductivity in M gCN i 3 was intensively studied. All of the known substitutions at Ni-site are found to decrease the superconducting temperature and/or bulk superconducting volume [10,11,12]. Normal state 13 C NMR measurement implies the existence of spin fluctuation above 20 K[4]. The calculated Stoner exchange parameter S = 0.43 ∼ 0.64 [7,13] and the Stoner renormalization is 5 [8]. The value is at the high edge of paramagnetic region and close to the ferromagnetic region which may lead to ferromagnetic spin fluctuation. *

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Raman and optical spectroscopic studies of small-to-large polaron crossover in the perovskite manganese oxides

Cited by 191 publications

References 32 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

Raman spectroscopy study of the interface structure in (CaCuO₂)_n/(SrTiO₃)_m superlattices

Optical properties ofMgCNi3in the normal state

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Raman and optical spectroscopic studies of small-to-large polaron crossover in the perovskite manganese oxides

Cited by 191 publications

References 32 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

Raman spectroscopy study of the interface structure in (CaCuO2)n/(SrTiO3)m superlattices

Optical properties ofMgCNi3in the normal state

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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

Raman spectroscopy study of the interface structure in (CaCuO₂)_n/(SrTiO₃)_m superlattices