Infrared-Active Vibrations of High-Temperature Superconductors: Experiment and Theory

Litvinchuk, A. P.; Thomsen, C.; Cardona, M.

doi:10.1142/9789814440981_0006

Cited by 22 publications

(11 citation statements)

References 188 publications

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“…At all temperatures investigated five optical phonon modes near 128, 151, 190, 288, and 654 cm −1 are clearly observed. It is well established [13][14][15] that the modes appearing in the spectra of anisotropic ceramics correspond to phonon modes polarized along c-axis. The ab-plane response from phonons in the reflectivity spectra (left panel, Fig.…”

Section: Resultsmentioning

confidence: 99%

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Phonon anomalies and electron-phonon interaction in theRuSr2GdCu2O
Boris
¹
,
Mandal
²
,
Bernhard
³

et al. 2001
Phys. Rev. B
24
3
8
2
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Critical behavior of the infrared reflectivity of RuSr2GdCu2O8 ceramics is observed near the superconducting TSC = 45 K and magnetic TM = 133 K transition temperatures. The optical conductivity reveals the typical features of the c-axis optical conductivity of strongly underdoped multilayer superconducting cuprates. The transformation of the Cu-O bending mode at 288 cm −1 to a broad absorption peak at the temperatures between T * = 90 K and TSC is clearly observed, and is accompanied by the suppression of spectral weight at low frequencies. The correlated shifts to lower frequencies of the Ru-related phonon mode at 190 cm −1 and the mid-IR band at 4800 cm −1 on decreasing temperature below TM are observed. It provides experimental evidence in favor of strong electron-phonon coupling of the charge carriers in the Ru-O layers which critically depends on the Ru core spin alignment. The underdoped character of the superconductor is explained by strong hole depletion of the CuO2 planes caused by the charge carrier self-trapping at the Ru moments.

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Section: Resultsmentioning

confidence: 99%

“…[14][15][16] Indeed, Ru-1212 is structurally similar to the rare-earth cuprate superconductors like Y-123 except that the Cu-O chain layers are replaced by RuO 2 square planar layers. Ignoring the rotations of the RuO 6 octahedra, an approximate structure is then of tetragonal symmetry P 4/mmm.…”

Section: Resultsmentioning

confidence: 99%

Phonon anomalies and electron-phonon interaction in theRuSr2GdCu2O
Boris
¹
,
Mandal
²
,
Bernhard
³

et al. 2001
Phys. Rev. B
24
3
8
2
View full text Add to dashboard Cite

show abstract

“…The spectra were obtained [7] by Kramers-Kronig transformation of reflectivity data of a ceramic sample consisting of microcrystals with random orientations. It is known, that sharper structures in the data of polycrystalline samples of high-T c compounds corresponds largely to the c-axis polarized phonons and that the metallic back-ground originates predominantly from the a-b conductivity (see [1] and Ref.…”

Section: Tlmentioning

confidence: 99%

“…Some of the phonon modes in the high-T c cuprate superconductors are strongly renormalized when going from the normal to the superconducting state [1,2,3,4,5,6,7,8,9,10].…”

Section: Introductionmentioning

confidence: 99%

Phonon anomalies in trilayer high-Tc cuprate superconductors

Dubroka

Munzar

2004

Physica C: Superconductivity

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We present an extension of the model proposed recently to account for dramatic changes below T c (anomalies) of some c-axis polarized infrared-active phonons in bilayer cuprate superconductors, that applies to trilayer high-T c compounds. We discuss several types of phonon anomalies that can occur in these systems and demonstrate that our model is capable of explaining the spectral changes occurring upon entering the superconducting state in the trilayer compound Tl 2 Ba 2 Ca 2 Cu 3 O 10 . The low-temperature spectra of this compound obtained by Zetterer and coworkers display an additional broad absorption band, similar to the one observed in underdoped YBa 2 Cu 3 O 7−δ and Bi 2 Sr 2 CaCu 2 O 8 . In addition, three phonon modes are strongly anomalous. We attribute the absorption band to the transverse Josephson plasma resonance, similar to that of the bilayer compounds. The phonon anomalies are shown to result from a modification of the local fields induced by the formation of the resonance. The spectral changes in Tl 2 Ba 2 Ca 2 Cu 3 O 10 are compared with those occurring in Bi 2 Sr 2 Ca 2 Cu 3 O 10 , reported recently by Boris and coworkers.

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“…The 1-3% softening of the B 2u vibration in the IR spectra (B 1g in the Raman spectra of double-layer cuprates) is actually observed in a large number of HTSC materials [82]. Moreover, these softenings, called above-T c anomalies, are probably a single common feature of the new superconductors that is dependably determined by spectroscopy [83].…”

Section: Appendixmentioning

confidence: 96%

Symmetry‐polarized unresticted Hartree‐Fock approach to transition metals in solids

Noda

Goroshkov

1997

Elect J Theoret Chem

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SUMMARYA direct numerical method for atomic electronic structure simulation of transition metals in matter is proposed in order to perform precise investigations of low-symmetry effects. Contrary to the spin-polarized unrestricted Hartree-Fock approach, well known as the different orbitals for different spins method, the radial orbitals are split in accordance with the site symmetry of the ion in the crystal and transformed under the irreducible representations of a given point group. In the frame of a free-atomic embedding scheme, the electronic structure of the transition metal ion is calculated with a non-spherical ab initio potential of nearest neighbours. An original procedure using a somewhat generalized Gram-Schmidt orthogonalization process is developed. Thus d-ion radial orbitals are orthogonalized to the appropriate ligand ones in a numerically self-consistent way. The theoretical content is illustrated by detailed calculations of transition metal d 9,10 configurations in a square planar Me : [O 2− ]4 system. To find the copper peculiarity a general picture of the electronic structure of such systems is given through a comparative study of Zn, Cu and Ni. The influence of small features in the radial electron distribution on spectra can be observed. Two types of excited electronic states recognized as susceptible to structure and overcontracted have been found. The comparison of calculations with free-atomic and 'embedded' ligand wave functions shows that an extremely large role is played by ligand spatial stretching in the close metal clusters. Also, some important features of high-Tc superconductivity are considered through calculations of d 9 -d 10 crossing revealed for copper in the cluster.

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Infrared-Active Vibrations of High-Temperature Superconductors: Experiment and Theory

Cited by 22 publications

References 188 publications

Phonon anomalies and electron-phonon interaction in theRuSr2GdCu2O
Boris
¹
,
Mandal
²
,
Bernhard
³

et al. 2001
Phys. Rev. B
24
3
8
2
View full text Add to dashboard Cite

Phonon anomalies and electron-phonon interaction in theRuSr2GdCu2O
Boris
¹
,
Mandal
²
,
Bernhard
³

et al. 2001
Phys. Rev. B
24
3
8
2
View full text Add to dashboard Cite

Phonon anomalies in trilayer high-Tc cuprate superconductors

Symmetry‐polarized unresticted Hartree‐Fock approach to transition metals in solids

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Infrared-Active Vibrations of High-Temperature Superconductors: Experiment and Theory

Cited by 22 publications

References 188 publications

Phonon anomalies and electron-phonon interaction in theRuSr2GdCu2OBoris1, Mandal2, Bernhard3 et al. 2001Phys. Rev. B24382View full textAdd to dashboardCite

Phonon anomalies and electron-phonon interaction in theRuSr2GdCu2OBoris1, Mandal2, Bernhard3 et al. 2001Phys. Rev. B24382View full textAdd to dashboardCite

Phonon anomalies in trilayer high-Tc cuprate superconductors

Symmetry‐polarized unresticted Hartree‐Fock approach to transition metals in solids

Contact Info

Product

Resources

About

Phonon anomalies and electron-phonon interaction in theRuSr2GdCu2O
Boris
¹
,
Mandal
²
,
Bernhard
³

et al. 2001
Phys. Rev. B
24
3
8
2
View full text Add to dashboard Cite

Phonon anomalies and electron-phonon interaction in theRuSr2GdCu2O
Boris
¹
,
Mandal
²
,
Bernhard
³

et al. 2001
Phys. Rev. B
24
3
8
2
View full text Add to dashboard Cite