Submillimeter and millimeter wave ESR measurements of one-dimensional edge-sharing CuO/sub 2/ chain system Ca/sub 2/Y/sub 2/Cu/sub 5/O/sub 10/

Submillimeter and millimeter wave ESR measurements of the one-dimensional CuO/sub 2/ chain system, Ca/sub 2/Y/sub 2/Cu/sub 5/O/sub 10/, have been performed using a pulsed magnetic field up to 16 T. The g-shift is observed between T/sub N/=30 K and 50 K. The frequency-field diagram observed at 1.8 K shows AFMR modes of the easy axis type, The magnetic properties of the AF (antiferromagnetic) state are discussed.