Phonon profiles in superconducting YNi2B2C and LuNi2B2C
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1999-11-01
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American Physical Society
Abstract
We performed a systematic inelastic neutron scattering, between 4 and 620 K, of the profiles of the anomalous acoustic and optic phonon observed in both compounds in the vicinity of <(xi)over right arrow>(m) congruent to (0.5 0 0). Above T-c we find that, in both compounds, the frequencies of the acoustic modes decrease with decreasing temperature and there is intensity transfer from-the upper (optic) to the lower (acoustic) mode. The frequencies of the optic modes of the Y compound, on the other hand, decrease slower than those of the Lu compound as the temperature decreases towards T-c and, as a result, the two branches approach each other in the Lu compound, whereas they separate in the Y compound. In both compounds the observed phonon profiles above T-c can be described satisfactorily in terms of a simple couple-mode model. Comparison of the phonon spectra of the two compounds below T-c demonstrates that the sharp peak at approximately 4 meV with a broad shoulder at the higher-energy side, observed in both compounds, arises from the change in the acoustic phonon profile upon entering the superconducting state.
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This article is published as Zarestky, J., C. Stassis, A. Goldman, P. Canfield, G. Shirane, and S. Shapiro. "Phonon profiles in superconducting YNi 2 B 2 C and LuNi 2 B 2 C." Physical Review B 60, no. 17 (1999): 11932.
DOI: 10.1103/PhysRevB.60.11932.
Copyright 1999 American Physical Society.
Posted with permission.