We have identified the optical phonon modes of high-quality superconducting infinite-layer compounds Sr0.9Ln0.1CuO2 (Ln = La and Sm, Tc = 43 K for both) from their infrared reflectivity spectra obtained with a Fourier-transform infrared spectrometer. The La-doped compound exhibited only four (2A2u + 2Eu) out of the five (2A2u + 3Eu) infrared-active phonon modes predicted by a group theoretical analysis, with one Eu mode screened by free carriers. The Sm-doped compound exhibited all five modes. We propose the displacement pattern for each mode based on reported lattice dynamics calculations and through comparison with the phonon modes of other single-layer high-Tc cuprates.
Bibliographical noteFunding Information:
MOM was supported by Basic Research Program for the Women Scientists of the Korea Science and Engineering Foundation for this work. JHK was supported by BK21 Project of Ministry of Education. And SIL was supported by the Creative Initiative Research Program of the Ministry of Science and Technology of Korea and KOSEF (contract no. 95-0702-03-03-3).
All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics
- Energy Engineering and Power Technology
- Electrical and Electronic Engineering