MAGNETIC RESONANCES AND MAGNETIZATION IN THE LOW-DIMENSIONAL SPIN SYSTEM CSNICL3

We present magentic resonance and magnetization measurements in the lo w dimensional spin system CsNiCl3 for temperatures down to 1.5 K and i n magnetic fields up to 14 T. The frequency range from 35 GHz to 380 G Hz is much larger than for previous experiments. The outstanding featu res of these experiments are a spreading of the magnetic resonance bra nches in high fields below T(N) and an upturn of the magnetization at higher fields and for temperatures below 20 K. Wheras we can interpret our resonance data with a six sublattice model invoking a large inter chain exchange, the magnetization points to typical one dimensional be haviour in higher fields. A theory for a consistent description of res onance data, spinwave spectra and magnetization is required.