Raman-active phonons and mode softening in superconducting HgBa[sub 2]CuO[sub 4+[delta]]

Journal Article · Fri Jul 01 00:00:00 EDT 1994 · Physical Review, B: Condensed Matter; (United States)

DOI:https://doi.org/10.1103/PhysRevB.50.1165· OSTI ID:7295827

Krantz, M C; Thomsen, C; Mattausch, H; Cardona, M ^[1]

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1. Max-Planck-Institut fuer Festkoerperforschung Heisenbergstrasse 1, D-70569 Stuttgart (Germany)

Polarized micro-Raman spectra of a single crystallite of HgBa[sub 2]CuO[sub 4+[delta]] have been measured and used to assign phonon modes of [ital A][sub 1[ital g]] and [ital E][sub [ital g]] symmetry intrinsic to the superconducting phase. Predictions of the peak positions, linewidths, and Raman cross sections from compounds with similar bonding, i.e., HgO, Y-124, and Y-123, are closely matched and suggest assignments of the high-frequency [ital A][sub 1[ital g]] modes at 592 and 568 cm[sup [minus]1] to apical oxygen stretch vibrations of the ideal structure and of a Cu or O defect (in the Hg plane). The low-frequency 168, 161, and 75 cm[sup [minus]1] modes are assigned to O and Ba vibrations of [ital E][sub [ital g]],[ital A][sub 1[ital g]] and [ital E][sub [ital g]] symmetry, respectively. An anomaly in the phonon frequency and linewidth of the 568-cm[sup [minus]1] [ital A][sub 1[ital g]] mode is observed below [ital T][sub [ital c]]. If interpreted as a change in the phonon self-energy due to the onset of superconductivity, this behavior is consistent with a gap energy near 568 cm[sup [minus]1], i.e., 8.7[ital kT][sub [ital c]] in HgBa[sub 2]CuO[sub 4+[delta]] and constitutes a first estimate of the superconducting gap in this material. The Raman tensor elements for the assigned [ital A][sub 1[ital g]] and [ital E][sub [ital g]] modes are given in absolute units.

• OSTI ID: 7295827
• Journal Information: Physical Review, B: Condensed Matter; (United States), Vol. 50:2; ISSN 0163-1829
• Country of Publication: United States
• Language: English

Related Subjects

75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
HIGH-TC SUPERCONDUCTORS
RAMAN SPECTRA
BARIUM OXIDES
COPPER OXIDES
CROSS SECTIONS
ENERGY GAP
LINE WIDTHS
MERCURY OXIDES
ALKALINE EARTH METAL COMPOUNDS
BARIUM COMPOUNDS
CHALCOGENIDES
COPPER COMPOUNDS
MERCURY COMPOUNDS
OXIDES
OXYGEN COMPOUNDS
SPECTRA
SUPERCONDUCTORS
TRANSITION ELEMENT COMPOUNDS
665411* - Basic Superconductivity Studies- (1992-)