Journal or Book Title
Physical Review B
We report polarized Raman results of magnetic superconductor DyNi2B2C (Tc=6.2 K, TN=10.3 K) to explore crystal-field (CF) excitations and spin-phonon interactions. In addition to the Ni-B1g phonon mode at 199 cm−1, we observed additional Raman modes at 124, 151, and 221 cm−1. By careful analysis of the temperature evolution of these modes, we attribute the 124 cm−1 excitation to a CF transition. The 151 and 221 cm−1 modes correspond to zone-folded phonons because they are completely quenched for T>TN. With increasing temperature across TN, the 124 cm−1 excitation diminishes rapidly in intensity and, interestingly, an additional mode appears at 119 cm−1. This excitation grows in intensity with increasing temperature toward 50 K and gradually decreases with increasing temperature further. We attribute the 119 cm−1 excitation to an excited CF transition from a low-lying CF level at 5 cm−1 to the higher CF level at 124 cm−1. Anomalous temperature-dependent behavior of the Ni-B1g phonon mode was observed in peak energy and in spectral width, i.e., both the phonon energy and the linewidth are enhanced in the vicinity of TN, suggesting the presence of strong spin-phonon interactions near the antiferromagnetic ordering temperature in DyNi2B2C.
American Physical Society
Rho, Heesuk; Klein, Miles V.; and Canfield, Paul C., "Crystal-field excitations and spin-phonon interactions in DyNi2B2C: Raman scattering study" (2010). Ames Laboratory Publications. 184.