Flat-band spin dynamics and phonon anomalies of the saw-tooth spin-chain system Fe${}_2$O(SeO${}_3$)${}_2$

V. P. Gnezdilov, Yu. G. Pashkevich, V. S. Kurnosov +11

Fe${}^{3+}$ $S=5/2$ ions form saw-tooth like chains along the $a$ axis of the oxo-selenite Fe${}_2$O(SeO${}_3$)${}_2$ and an onset of long-range magnetic order is observed for temperatur…