NUCLEAR-MAGNETIC-RESONANCE IN HIGH MAGNETIC-FIELDS - STUDY OF SINGLET-GROUND-STATE DUE TO 1-D QUANTUM SPIN EFFECT

In one-dimensional (1-D) magnets the singlet-ground-state (SGS) due to the quantum spin effect is one of the most interesting phenomena. The temperature and the field dependences of the proton spin-lattice rela xation under magnetic fields up to 15 T have been observed for SGS mat erials, namely, NENP (Haldane system) and CuCl2(gamma-picoline)(2) (al ternating antiferromagnetic chain). The results clearly show the excit ation of SGS with a characteristic energy gap in the magnetic excited state. The observed relaxation rate is discussed in terms of the numbe r of magnetic excitons in focussing on the dissimilarity between two s ystems.