Raman study of the oxygen anharmonicity in YBa2Cu3Ox (6.4<x<7.0) superconductors

D. Palles; N. Poulakis; E. Liarokapis; K. Conder; E. Kaldis; K. A. Müller

doi:10.1103/PhysRevB.54.6721

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Raman study of the oxygen anharmonicity in YBa2Cu3Ox (6.4<x<7.0) superconductors

D. Palles, N. Poulakis, E. Liarokapis, K. Conder, E. Kaldis, K. A. Müller

DOI 10.1103/PhysRevB.54.6721 · Physical Review B

T1

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Abstract

A systematic Raman study in the visible and the near IR has been carried out on YBa2Cu3Ox samples, with isotopic substitution of O18 for O16, and for oxygen concentrations in the range x=6.44−6.98. A small but clear deviation from harmonic behavior has been detected for the frequency shift of the in-phase mode and, to a less extent, of the apex mode, relative to the out-of-phase phonon. The deviation increases towards low concentrations of oxygen. A disagreement of the present work for the apical mode, with a previous investigation using IR excitation, is attributed to the contribution of several phases to the apex mode in the underdoped region and the possible IR resonance of the "ortho-II" phase.

Source-reported materials — not catalogue approval

Formula	Reported Tc (K)	Pressure (GPa)	Type
YBa2Cu3Ox Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	—	Pressure not reported	unknown
YBa2Cu316Ox Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	—	Pressure not reported	unknown
YBa2Cu318Ox Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	—	Pressure not reported	unknown