INVESTIGATION OF THE SPIN-PEIERLS PHASE-DIAGRAM OF CUGEO3 - FAR-INFRARED ELECTRON-SPIN-RESONANCE IN HIGH-FIELD

Electron spin resonance on single crystals of the spin-Peierls compoun d CuGeO3 has been performed in magnetic fields up to 17 T in the tempe rature range 1.8-20k. Using far-infrared laser frequencies of 245 and 525 GHz we could observe resonance conditions in the three different m agnetic phases, i.e., the uniform, the dimerized, and the incommensura te phases for a magnetic field appliedk parallel to the a axis of the crystal. So far the first time data on electron spin dynamics in the i ncommensurate phase are reported for fields far from the transition to the dimerised phase. Striking effects concerning the g factor, linewi dth, and hysteresis are observed. (C) 1996 American Institute of Physi cs.