TY - JOUR
T1 - First-principles study of elastic and phonon properties of the heavy fermion compound CeMg
AU - Shang, S. L.
AU - Hector, L. G.
AU - Wang, Y.
AU - Zhang, H.
AU - Liu, Z. K.
PY - 2009
Y1 - 2009
N2 - Elasticity tensor components, Cij, the crystallographic dependence of Poisson's ratio, the phase stability, and vibrational spectra are computed for nonmagnetic and magnetic CeMg (1:1 Ce:Mg) structures using density functional theory. Results from both the generalized gradient approximation (GGA), and the GGA+U, based upon an effective on-site Coulomb potential, U eff, are investigated. The GGA low energy structure, with wavevector along [110], disagrees with experiment, while the [100] structure from experiment is predicted as the 0K structure in the GGA+U. Accurate estimation of the 20K Néel temperature can only be achieved with small U eff, which suggests that CeMg is not a strongly correlated system. For all CeMg structures investigated, we find C11≈C44; this is consistent with the near equivalency of transverse and longitudinal sound speeds. The origin of this behavior is the negative stretching force constants for the interaction between the second-and third-nearest-neighbor Mg and Ce ions, respectively. Results are compared with neutron scattering experiments at 30 and 110K.
AB - Elasticity tensor components, Cij, the crystallographic dependence of Poisson's ratio, the phase stability, and vibrational spectra are computed for nonmagnetic and magnetic CeMg (1:1 Ce:Mg) structures using density functional theory. Results from both the generalized gradient approximation (GGA), and the GGA+U, based upon an effective on-site Coulomb potential, U eff, are investigated. The GGA low energy structure, with wavevector along [110], disagrees with experiment, while the [100] structure from experiment is predicted as the 0K structure in the GGA+U. Accurate estimation of the 20K Néel temperature can only be achieved with small U eff, which suggests that CeMg is not a strongly correlated system. For all CeMg structures investigated, we find C11≈C44; this is consistent with the near equivalency of transverse and longitudinal sound speeds. The origin of this behavior is the negative stretching force constants for the interaction between the second-and third-nearest-neighbor Mg and Ce ions, respectively. Results are compared with neutron scattering experiments at 30 and 110K.
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U2 - 10.1088/0953-8984/21/24/246001
DO - 10.1088/0953-8984/21/24/246001
M3 - Article
AN - SCOPUS:66349118579
VL - 21
JO - Journal of Physics Condensed Matter
JF - Journal of Physics Condensed Matter
SN - 0953-8984
IS - 24
M1 - 246001
ER -