Anharmonicity and Weak Mode Assignment in La_{2-x}Sr_xCuO_4, with Oxygen Isotopic Substitution

• Authors: E. Siranidi , D. Lampakis , D. Palles , E. Liarokapis , K. Conder
• Languages of publication: EN

Abstracts

EN

The oxygen isotope effect on the first- and second-order Raman active modes of high-quality La_{2-x}Sr_xCu^{16,18}O_4 (80% substitution ^{16}O by ^{18}O) polycrystalline compounds with x=0.00, 0.015 was investigated at low temperatures. In the second-order Raman scattering several weak and strong peaks were observed and assigned to oxygen atom vibrations. With the isotopic substitution the apex oxygen mode follows quite well the mass harmonic law at all temperatures studied, while the soft mode is anharmonic in the temperature range of 77-180 K and for higher temperatures its anharmonicity is strongly increased. The temperature dependence of the energy of the soft mode for x=0.0 shows also a modification at≈180 K and an abnormal behaviour at≈280 K, which may be related with the transition to the antiferromagnetic phase.

Keywords

EN

78.30.-j; 31.30.Gs; 74.25.Kc; 74.72.Dn

Discipline

• 74.25.Kc: Phonons
• 31.30.Gs: Hyperfine interactions and isotope effects(see also 32.10.Fn Fine and hyperfine structure)
• 78.30.-j: Infrared and Raman spectra(for vibrational states in crystals and disordered systems, see 63.20.-e and 63.50.-x, respectively; for Raman spectra of superconductors, see 74.25.nd)

• Journal: Acta Physica Polonica A
• Year: 2007
• Volume: 111
• Issue: 1
• Pages: 173-177

Dates

published

2007-01

received

2006-09-04

Contributors

author

E. Siranidi

• Department of Physics, National Technical University, Athens 157 80, Greece

author

D. Lampakis

• Department of Physics, National Technical University, Athens 157 80, Greece

author

D. Palles

• Department of Physics, National Technical University, Athens 157 80, Greece

author

E. Liarokapis

• Department of Physics, National Technical University, Athens 157 80, Greece

author

K. Conder

• Paul Scherrer Institut (PSI) WLGA, Villigen PSI 5232, Switzerland

References

• 1. B. Keimer, N. Belk, R.J. Birgeneau, A. Cassanho, C.Y. Chen, M. Greven, M.A. Kastner, A. Aharony, Y. Endoh, R.W. Erwin, G. Shirane, Phys. Rev. B. 46. 14034, 1992
• 2. S. Sugai, Phys. Rev. B. 39. 4306, 1989
• 3. W.M. Weber, C.R. Peters, E.M. Logothetis, J. Opt. Soc. Am.. 6. 455, 1989
• 4. W.M. Weber, C.R. Peters, B.M. Wanklyn, C. Chen, B.E. Watts, Phys. Rev. B. 38, 917, 1988
• 5. D. Lampakis, Ph.D. Thesis, National Technical University of Athens, Department of Physics, Athens 2002, p. 100

Identifiers

DOI

10.12693/APhysPolA.111.173