The MacDiarmid Institute for Advanced Materials and Nanotechnology and The School of Chemical and Physical Sciences, Victoria University of Wellington, P.O. Box 600, Wellington 6140, New Zealand
R. G. Buckley
The MacDiarmid Institute for Advanced Materials and Nanotechnology and The Robinson Research Institute, Victoria University of Wellington, P.O. Box 600, Wellington 6140, New Zealand
T. J. Butler
The MacDiarmid Institute for Advanced Materials and Nanotechnology and The Robinson Research Institute, Victoria University of Wellington, P.O. Box 600, Wellington 6140, New Zealand
C. Pot
The MacDiarmid Institute for Advanced Materials and Nanotechnology and The School of Chemical and Physical Sciences, Victoria University of Wellington, P.O. Box 600, Wellington 6140, New Zealand
K. Van Koughnet
The MacDiarmid Institute for Advanced Materials and Nanotechnology and The School of Chemical and Physical Sciences, Victoria University of Wellington, P.O. Box 600, Wellington 6140, New Zealand
B. J. Ruck
The MacDiarmid Institute for Advanced Materials and Nanotechnology and The School of Chemical and Physical Sciences, Victoria University of Wellington, P.O. Box 600, Wellington 6140, New Zealand
H. J. Trodahl
The School of Chemical and Physical Sciences, Victoria University of Wellington, P.O. Box 600, Wellington 6140, New Zealand
Far infrared measurements of the absorption into the IR-active TO(Γ) mode are reported for a selection of the rare-earth mononitrides. The frequencies harden as anticipated by ≈15% as the lattice constant shrinks by ≈6% from SmN to LuN, though they are typically ∼25% softer than the LSDA+U prediction published a decade ago. The data are in much closer agreement with our computation based on more recent software for two in the series: GdN and LuN. The resonances show surprisingly heavy damping, diminishing from the lighter to heavier rare earth elements.
