Dynamics in the dimerised and high field incommensurate phase of CuGeO${}_3$

Abstract

Temperature ($2.3<T<40$\ K) and magnetic field ($0<B<17$\ T) dependent far infrared absorption spectroscopy on the spin-Peierls coumpound CuGeO${}_3$\ has revealed several new absorption processes in both the dimerised and high field phase of CuGeO${}_3$. These results are discussed in terms of the modulation of the CuGeO${}_3$\ structure. At low fields this is the well known spin-Peierls dimerisation. At high fields the data strongly suggests a field dependent incommensurate modulation of the lattice as well as of the spin structure.

12 pages (revtex), 2 figures (eps), csh selfextracting .uu file, To appear in PRB-Rapid Comm