TO(Gamma) mode resonances in the rare-earth nitrides

Far infrared measurements of the absorption into the IR-active TO (Gamma) mode are reported for a selection of the rare-earth mononitrides. The frequencies harden as anticipated by approximate to 15% as the lattice constant shrinks by approximate to 6% from SmN to LuN, though they are typically similar to 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. (C) 2022 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution (CC BY) license