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

Journal Article · Fri Jul 01 04:00:00 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]

---

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

Related Subjects

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